LocalPresenceOwner BeginSubscribe throws InvalidOperation Exception

Hello,

   I have an established UserEndpoint and I want to be notified when other users subscribe to this UserEndpoint's presence.  When LocalPresenceOwner BeginSubscribe is called, I am getting the following InvalidOperation exception.  I must be missing a step somewhere.  

System.InvalidOperationException was unhandled by user code

  Message=The data session is in an invalid state to establish.
  Source=Microsoft.Rtc.Collaboration
  StackTrace:
       at Microsoft.Rtc.Collaboration.Presence.LocalOwnerPresence.BeginSelfSubscribeCore(SubscriptionChecks subscriptionChecks, Boolean useApplicationQueue, AsyncCallback userCallback, Object state)
       at Microsoft.Rtc.Collaboration.Presence.LocalOwnerPresence.BeginSubscribeCore(SubscriptionChecks subscriptionChecks, Boolean useApplicationQueue, AsyncCallback userCallback, Object state)
       at Microsoft.Rtc.Collaboration.Presence.PublishSubscribeSession.BeginSubscribe(AsyncCallback userCallback, Object state)
       at appIcLync.IcLyncMgr.EndEndpointEstablish(IAsyncResult ar) in C:\Users\administrator\Documents\Visual Studio 2010\Projects\appIcLync\appIcLync\IcLyncMgr.cs:line 304
       at Microsoft.Rtc.Signaling.CompletionCallbackWorkItem.Microsoft.Rtc.Signaling.IWorkitem.Process()
       at Microsoft.Rtc.Signaling.WorkitemQueue.ProcessItems()
       at Microsoft.Rtc.Signaling.SerializationQueue`1.ResumeProcessing()
       at Microsoft.Rtc.Signaling.SerializationQueue`1.ResumeProcessingCallback(Object state)
       at Microsoft.Rtc.Signaling.QueueWorkItemState.ExecuteWrappedMethod(WaitCallback method, Object state)
  InnerException: 

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What step am I missing?

Thanks,

Matt