xbox live problem, mx vs atv unleashed?

[billzfan07]

i like to play mx vs atv unleashed on xbox live and i use a wireless network to connect, but whenever i try to play on one of the online matches it will either say "cant connect because of network conifguration" or something like that or it will say "this game session is not available". although i can play on only 1 or 2 out of alll of them. y is this and it is really making me mad.