Unable to receive v3 traps/informs with SharpSNMP - snmp

Question

Using the snmptrapd example I was able to receive v1 traps and v2 traps/informs easily. However, with v3 I am unable to receive traps. I am using AES128 and SHA1 for Privacy and Authentication.
When I "wireshark" port 162 I see "encryptedPDU: privKey unknown" coming from the device I am attempting to receive traps from. It is using NET-SNMP if that helps.
I was able to implement applications using SharpSNMP for gets and sets with no problem. What am I missing here?
Code snippet below:
Note: engine.Start() is called form the instantiating class.
registry = new UserRegistry();
var authProvider = new SHA1AuthenticationProvider(new OctetString("authsecret"));
var privacyProvider = new AESPrivacyProvider(new OctetString("privsecret"), authProvider);
registry.Add(new OctetString("informuser"), privacyProvider);
registry.Add(new OctetString("trapuser"), privacyProvider);
TrapV1Handler = new TrapV1MessageHandler();
TrapV1Handler.MessageReceived += WatcherTrapV1Received;
v1Mapping = new HandlerMapping("v1", "TRAPV1", TrapV1Handler);
TrapV2Handler = new TrapV2MessageHandler();
TrapV2Handler.MessageReceived += WatcherTrapV2Received;
v2Mapping = new HandlerMapping("v2,v3", "TRAPV2", TrapV2Handler);
InformHandler = new InformRequestMessageHandler();
InformHandler.MessageReceived += WatcherInformRequestReceived;
informMapping = new HandlerMapping("v2,v3", "INFORM", InformHandler);
store = new ObjectStore();
var v1 = new Version1MembershipProvider(new OctetString("public"), new OctetString("public"));
var v2 = new Version2MembershipProvider(new OctetString("public"), new OctetString("public"));
var v3 = new Version3MembershipProvider();
var membership = new ComposedMembershipProvider(new IMembershipProvider[] {v1, v2, v3});
var handlerFactory = new MessageHandlerFactory(new[] {v1Mapping, v2Mapping, informMapping});
var pipelineFactory = new SnmpApplicationFactory(store, membership, handlerFactory);
engine = new SnmpEngine(pipelineFactory, new Listener { Users = registry }, new EngineGroup());
engine.Listener.AddBinding(new IPEndPoint(IPAddress.Any, 162));
engine.ExceptionRaised += this.DoSomething;
}
private void DoSomething(object sender, ExceptionRaisedEventArgs args)
{
// never gets here
}
private void WatcherInformRequestReceived(object sender, InformRequestMessageReceivedEventArgs e)
{
// or here for v3 (works fine for v2)
}
private void WatcherTrapV2Received(object sender, TrapV2MessageReceivedEventArgs e)
{
// or here for v3 (works fine for v2)
}
private void WatcherTrapV1Received(object sender, TrapV1MessageReceivedEventArgs e)
{
// works fine
}