cant hear my game when on ts2

[bluntman]

my problem is that: have got a gamesurround muse xl that I buy today. When I start to speak with ts2, everything is ok : Ican hear and talk other. But when I enter the game(medal of honor), I doesn't hear the sound of the game.

configuration:

P4 1,6ghz
ge Force 2 mx400
gamesurround muse XL
motherboard ASUS p4B266


please help me