RaiseEvent failing. Event can't be sent!

As title says I have a problem with RaiseEvent() function.
I am trying to call RaiseEvent() inside OnLeftRoom()method but event can't be sent. I am almost sure the reason is that the player has already left the room when the event is trying to be sent. I am trying to find a way to delay player disconnect but I am afraid I can't find anything.
Any suggestions?