Error Message: Unable to participate in this session

I get an error message that says “Unable to participate in this session” any time I try to invite a friend to a private match. I’m playing on PC and use a BT Voyager router, its a cable connection and I have tried to forward my ports but the instructions at dont cover SF4 on the PC for BT routers.

Anyone have any idea how to rectify this? Its a real pain in the ass.

Try harder next time.