MessageEventManager Is Not Working for Me. It also says Exception in packet listener. Can someone help me?

MessageEventManager Is Not Working for Me. It also says Exception in packet listener. I Tried The Smack Code On GitHub but still it did not work for me. Can someone help me?

We are unable to help you, if you don’t provide further information. Start with the type of the exception, the full stacktrace of the exception and a few code samples.