When releasing the Phone monitor, i dont seem to be getting any events returned. I have subscribed to the Phone.onStopPhoneMonitorResponse , and created the method that should capture the event when its received. but its no use.
Is there anything that i'm missing?

Take a look at the log file in AE Services to see what occurs when you send your request.

/opt/mvap/logs/dmcc-trace.log.0

If that doesn't clue you into what is wrong, increase the XML logging by using the instructions in the FAQ that is titled "How can I monitor the XML being sent and received by the AE Services Server (debug, log, trace)?"

Usually when you get no response at all, there is some problem with the request (poorly encoded message, bad XML format).

This is what i get it the log file u can see the main parts on top and in the bottom. Is that the correct response xml i'm gettint for a stopMonitor request?

2013-07-10 17.52.22,414 :T-66: com.avaya.proxy.castor.CastorUnmarshaller unmarshal
FINEST: Unmarshalling a <?xml version="1.0" encoding="utf-8"?>
<MonitorStop xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns="http://www.ecma-international.org/standards/ecma-323/csta/ed3">
<monitorCrossRefID>1</monitorCrossRefID>
</MonitorStop>
2013-07-10 17.52.22,414 :T-66: com.avaya.proxy.castor.CastorUnmarshaller unmarshal
FINER: XML Mapping enum: NO_MAPPING, org.exolab.castor.xml.util.ClassDescriptorResolverImpl@1860570
2013-07-10 17.52.22,415 :T-66: com.avaya.proxy.castor.CastorUnmarshaller unmarshal
FINER: Unmarshalled a session[null] ch.ecma.csta.binding.MonitorStop@864587
2013-07-10 17.52.22,415 :T-66: com.avaya.mvcs.proxy.CstaUnmarshallerNode$CstaUnmarshallerProcessorThread run
FINEST: Actual unmarshall time is : 1ms : thread=Thread[pool-7-thread-1,5,main]
2013-07-10 17.52.22,415 :T-66: com.avaya.mvcs.proxy.CstaUnmarshallerNode$CstaUnmarshallerProcessorThread run
FINEST: Unmarshalled xml=<?xml version="1.0" encoding="utf-8"?>
<MonitorStop xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns="http://www.ecma-international.org/standards/ecma-323/csta/ed3">
<monitorCrossRefID>1</monitorCrossRefID>
</MonitorStop> to object=session[null] ch.ecma.csta.binding.MonitorStop@864587
2013-07-10 17.52.22,416 :T-66: com.avaya.common.nio.managed.tr87Impl.TR87RequestRegulator addUnmarshallTime
FINEST: adding unmarshall time: 3ms
2013-07-10 17.52.22,416 :T-66: com.avaya.common.nio.managed.defaultImpl.DefaultTCPChannel getLocalSocketAddress
FINER: getLocalSocketAddress called.
2013-07-10 17.52.22,416 :T-66: com.avaya.mvcs.proxy.CstaRouterNode processPacket
FINER: CstaRouterNode: PUBLISHER CHANNEL IS= asyncDefaultTCPChannel Bound to SocketAddress: /172.22.100.20:4721 Connected to SocketAddress: /172.21.150.13:5676136
2013-07-10 17.52.22,416 :T-66: com.avaya.common.nio.managed.defaultImpl.DefaultTCPChannel getLocalSocketAddress
FINER: getLocalSocketAddress called.
2013-07-10 17.52.22,416 :T-66: com.avaya.mvcs.proxy.SubscriptionManager subscribeAsyncResponse
FINER: adding EventSubscriber to channel=asyncDefaultTCPChannel Bound to SocketAddress: /172.22.100.20:4721 Connected to SocketAddress: /172.21.150.13:5676136
2013-07-10 17.52.22,416 :T-66: com.avaya.mvcs.proxy.CstaRouterNode processPacket
FINER: Adding: Subscription Manager count= 3 request=session[null] ch.ecma.csta.binding.MonitorStop@864587 channel=asyncDefaultTCPChannel Bound to SocketAddress: /172.22.100.20:4721 Connected to SocketAddress: /172.21.150.13:5676136
2013-07-10 17.52.22,416 :T-66: com.avaya.mvcs.proxy.SubscriptionManager unsubscribe
FINER: Removing EventSubscriber from channel=1
2013-07-10 17.52.22,417 :T-66: com.avaya.mvcs.proxy.CstaRouterNode processPacket
FINE: invokeID= 36 Routing request=session[session FC5D0FD68549BEAA52AD59B38704CC3E-0] ch.ecma.csta.binding.MonitorStop@864587
2013-07-10 17.52.22,417 :T-66: com.avaya.workflow.impl.RouterImpl resolveArgs
FINER: RouterImpl: invokeid= 36 request= session[session FC5D0FD68549BEAA52AD59B38704CC3E-0] ch.ecma.csta.binding.MonitorStop@864587
2013-07-10 17.52.22,417 :T-66: com.avaya.async.impl.AsyncCallbackImpl <init>
FINER: AsyncCallbackImpl:36
2013-07-10 17.52.22,417 :T-66: com.avaya.workflow.impl.RouterImpl routeRequest
FINER: RouterImpl: routing request= session[session FC5D0FD68549BEAA52AD59B38704CC3E-0] ch.ecma.csta.binding.MonitorStop@864587
2013-07-10 17.52.22,417 :T-66: com.avaya.common.nio.managed.defaultImpl.DefaultTCPChannel getLocalSocketAddress
FINER: getLocalSocketAddress called.
2013-07-10 17.52.22,417 :T-66: com.avaya.platform.broker.impl.AsyncServiceMethodImpl invoke
FINER: Invoking method=public synchronized void com.avaya.cmapi.monitor.MonitoringServicesImpl.stopMonitor(ch.ecma.csta.binding.MonitorStop,com.avaya.api.async.AsynchronousCallback) throws ch.ecma.csta.errors.InvalidParameterValueException,ch.ecma.csta.errors.InvalidMonitorCrossRefIDException with argument=session[session FC5D0FD68549BEAA52AD59B38704CC3E-0] ch.ecma.csta.binding.MonitorStop@864587 publisher channel is= async DefaultTCPChannel Bound to SocketAddress: /172.22.100.20:4721 Connected to SocketAddress: /172.21.150.13:56761 invokeId=36
2013-07-10 17.52.22,417 :T-66: com.avaya.common.nio.managed.defaultImpl.DefaultTCPChannel getLocalSocketAddress
FINER: getLocalSocketAddress called.
2013-07-10 17.52.22,417 :T-66: com.avaya.cmapi.monitor.MonitoringServicesImpl stopMonitor
FINEST: received request to remove listener: crossRef=1
2013-07-10 17.52.22,417 :T-66: com.avaya.cmapi.monitor.MonitoringServicesImpl stopMonitor
FINE: removed PhysicalDeviceListener: crossRef=1:[Holder]: [32900449:CM5:0.0.0.0:0] ,com.avaya.cmapi.monitor.PhysicalDeviceListenerImpl@c51d92,session FC5D0FD68549BEAA52AD59B38704CC3E-0
2013-07-10 17.52.22,417 :T-66: com.avaya.cmapi.monitor.MonitoringServicesImpl stopMonitor
FINE: removed RegistrationListener: crossRef=1:[Holder]: [32900449:CM5:0.0.0.0:0] ,com.avaya.cmapi.monitor.RegistrationListenerImpl@1787280,session FC5D0FD68549BEAA52AD59B38704CC3E-0
2013-07-10 17.52.22,417 :T-66: com.avaya.cmapi.monitor.MonitoringServicesImpl releaseCrossRefId
FINE: released crossRefID=1: 1 are now in use, 79999 still available.
2013-07-10 17.52.22,417 :T-66: com.avaya.cmapi.monitor.MonitoringServicesImpl stopMonitor
FINE: removed monitor=1
2013-07-10 17.52.22,417 :T-66: com.avaya.cmapi.monitor.MonitoringServicesReplicator delete
FINER: 1: deleting crossRefId from persistent store
2013-07-10 17.52.22,418 :T-66: com.avaya.common.persistence.FileStore delete
FINER: Deleted /var/log/avaya/aes/resq/FC5D0FD68549BEAA52AD59B38704CC3E-0/mon/1
2013-07-10 17.52.22,418 :T-66: com.avaya.cmapi.monitor.MonitoringServicesImpl stopMonitor
FINE: stopped monitor=1: 1 remain in use, 79999 still available.
2013-07-10 17.52.22,418 :T-66: com.avaya.platform.broker.impl.AsyncServiceMethodImpl$MyResponseObserver setResponse
FINER: MyResponseObserver: invokeId= 36 publisher= [asyncDefaultTCPChannel Bound to SocketAddress: /172.22.100.20:4721 Connected to SocketAddress: /172.21.150.13:5676136]
2013-07-10 17.52.22,418 :T-66: com.avaya.mvcs.proxy.CstaRouterNode processPacket
FINE: invokeID= 36 Received com.avaya.platform.broker.impl.AsyncResponse@32d2e1 in response to session[session FC5D0FD68549BEAA52AD59B38704CC3E-0] ch.ecma.csta.binding.MonitorStop@864587
2013-07-10 17.52.22,418 :T-66: com.avaya.common.nio.managed.defaultImpl.DefaultTCPChannel getLocalSocketAddress
FINER: getLocalSocketAddress called.
2013-07-10 17.52.22,418 :T-69: com.avaya.common.nio.managed.defaultImpl.DefaultTCPChannel getLocalSocketAddress
FINER: getLocalSocketAddress called.
2013-07-10 17.52.22,418 :T-66: com.avaya.mvcs.proxy.CstaRouterNode processPacket
FINER: Returned from processing an AsyncrhonousReqeust session=session[session FC5D0FD68549BEAA52AD59B38704CC3E-0,DefaultTCPChannel Bound to SocketAddress: /172.22.100.20:4721 Connected to SocketAddress: /172.21.150.13:56761]
2013-07-10 17.52.22,418 :T-66: com.avaya.common.util.concurrent.impl.BasicMappingThreadPool$MyThreadPoolExecutor afterExecute
FINEST: Runnable com.avaya.common.util.concurrent.impl.TimeComparableRunnableWrapper@1b659c8 has finished
2013-07-10 17.52.22,418 :T-69: com.avaya.mvcs.proxy.SubscriptionManager$AsyncEventSubscriber$SubscriptionEvent run
FINER: Handling a class com.avaya.workflow.MessageContextTuple, session=session[session FC5D0FD68549BEAA52AD59B38704CC3E-0,DefaultTCPChannel Bound to SocketAddress: /172.22.100.20:4721 Connected to SocketAddress: /172.21.150.13:56761] invokeID=36
2013-07-10 17.52.22,418 :T-66: com.avaya.common.util.concurrent.impl.BasicMappingThreadPool$MyThreadPoolExecutor afterExecute
FINEST: com.avaya.common.util.concurrent.impl.TimeComparableRunnableWrapper@1b659c8 cancelling timer taskcom.avaya.common.util.concurrent.impl.WatchTask@17f5075
2013-07-10 17.52.22,418 :T-69: com.avaya.common.nio.managed.defaultImpl.DefaultTCPChannel getLocalSocketAddress
FINER: getLocalSocketAddress called.
2013-07-10 17.52.22,418 :T-66: com.avaya.common.util.concurrent.impl.BasicMappingThreadPool$MyThreadPoolExecutor afterExecute
FINEST: FC5D0FD68549BEAA52AD59B38704CC3E-0: no items found in the queue
2013-07-10 17.52.22,418 :T-69: com.avaya.mvcs.proxy.CstaMarshallerNode processPacket
FINEST: [Begin] payload=class ch.ecma.csta.binding.MonitorStopResponse, id=36, session=session[session FC5D0FD68549BEAA52AD59B38704CC3E-0,DefaultTCPChannel Bound to SocketAddress: /172.22.100.20:4721 Connected to SocketAddress: /172.21.150.13:56761]
2013-07-10 17.52.22,418 :T-69: com.avaya.mvcs.proxy.CstaMarshallerNode$CstaMarshallerThread <init>
FINEST: Marshaller: NO_MAPPING, protocolVersion: http://www.ecma-international.org/standards/ecma-323/csta/ed3/priv6
2013-07-10 17.52.22,418 :T-69: com.avaya.mvcs.proxy.CstaMarshallerNode$CstaMarshallerThread run
FINER: Packaging a session[null] ch.ecma.csta.binding.MonitorStopResponse@17b4ab6
2013-07-10 17.52.22,419 :T-69: com.avaya.mvcs.proxy.CstaMarshallerNode$CstaMarshallerThread run
FINEST: Marshalled session[null] ch.ecma.csta.binding.MonitorStopResponse@17b4ab6 to <?xml version="1.0" encoding="UTF-8"?>
<MonitorStopResponse xmlns="http://www.ecma-international.org/standards/ecma-323/csta/ed3"/>
2013-07-10 17.52.22,419 :T-69: com.avaya.common.nio.managed.defaultImpl.DefaultTCPChannel getLocalSocketAddress
FINER: getLocalSocketAddress called.
2013-07-10 17.52.22,419 :T-69: com.avaya.mvcs.proxy.ByteBufferToChannelNode processPacket
FINER: Writing ByteBuffer=java.nio.HeapByteBuffer[pos=0 lim=139 cap=139], session=session[session FC5D0FD68549BEAA52AD59B38704CC3E-0,DefaultTCPChannel Bound to SocketAddress: /172.22.100.20:4721 Connected to SocketAddress: /172.21.150.13:56761]
2013-07-10 17.52.22,419 :T-69: com.avaya.common.nio.managed.defaultImpl.DefaultTCPChannel getLocalSocketAddress
FINER: getLocalSocketAddress called.
2013-07-10 17.52.22,419 :T-69: com.avaya.mvcs.proxy.ByteBufferToChannelNode processPacket
FINEST: Wrote 139 of 139 bytes to the Channel, session=session[session FC5D0FD68549BEAA52AD59B38704CC3E-0,DefaultTCPChannel Bound to SocketAddress: /172.22.100.20:4721 Connected to SocketAddress: /172.21.150.13:56761]
2013-07-10 17.52.22,419 :T-69: com.avaya.mvcs.proxy.CstaMarshallerNode$CstaMarshallerThread run
FINEST: pool-9-thread-1: Duration of marshalling = 1msec and null publishing = 0msecs, session[null] ch.ecma.csta.binding.MonitorStopResponse@17b4ab6
2013-07-10 17.52.22,419 :T-69: com.avaya.mvcs.proxy.CstaMarshallerNode processPacket
FINEST: [End]

and is monitorcrossrefId the ID of the monitor that needs to get released? because
<MonitorStop xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns="http://www.ecma-international.org/standards/ecma-323/csta/ed3">
<monitorCrossRefID>1</monitorCrossRefID>
</MonitorStop>
1 was not the correct value?

AE Services clearly got your requst, processed it successfully and sent a response

<MonitorStopResponse xmlns="http://www.ecma-international.org/standards/ecma-323/csta/ed3"/>

Thus my conclusion is there is something wrong with your event handler setup. I suggest you take a look at the DMCC Popup app and study how it handles the onStopMonitorResponse for a phone monitor

https://devconnect.avaya.com/public/dyn/d_dyn.jsp?fn=656

You can enable logging in the DMCC .NET SDK to prove the monitorStop got that far.. my guess is there is missing plumbing between your application and the SDK (e.g. the initialization has a mistake somewhere).