ObjectAdded event in c#

Does anyone have the ObjectAdded and ObjectRemoved events working in a c# app? I can make them work in c++, but I never called in c#. Other system events to work.Here's the code: _simconnect.SubscribeToSystemEvent(AI_AIRCRAFT_LIFE_EVENTS.ADDED, "ObjectAdded"); _simconnect.SubscribeToSystemEvent(AI_AIRCRAFT_LIFE_EVENTS.REMOVED, "ObjectRemoved"); _simconnect.SubscribeToSystemEvent(AI_AIRCRAFT_LIFE_EVENTS.TEST, "4sec");I get a call back every 4 seconds, but never when FSX adds or removes an AI aircraft.So just before I give up, and port everything to c++, anyone been here before?Simon