TheTruePredator

Hi I was wondering if anyone can help me everytime (10 attempts) my mate sends me an invite for multiplayer it says the game no longer exists. I have a NAT type 2 with UPnP enabled. My other mate who has the same ISP can join straight away. I rang them to see what was going and the match was still running. I am stumped and don't have a clue how to fix this problem. Thanks for the help