i changed to OSS because now i can run Youtube Flash Videos and Tuxguitar at the same timer

But i have some problems, i only hear sound from the right speaker? I mean, there is sound from the left but its so quite its almost not hearable
In this screenshot, it looks like the left side is quite louder, but actually, i just heard the right speaker, the left one was nearly quite
http://www.abload.de/image.php?img=screen0xf8.png
These are my settings for now, do you know what i have to tweak to get everything work properly?
http://picfront.de/d/7XXC
greetings