Error DR1002 with Party

Hello, 

i got the problem that if i try to start the online mode with my brother in my party i get an Error "Disconnected" unable to connect DR1002 and get send back to the menu, if i join a game and inv him while i am allready on the server i get disconnected. If we try to join a server each, there is no problem with joining.

Any ideas how to fix?