Recordings don't record sound in GMOD

[rogue]

Whenever I'm recording with any program (I've used OBS, Fraps and Raptr) it doesn't seem to want to pick up the in game sound from Gmod. So obviously I know it's the game. Does anyone know a way to fix this?

EDIT
Sound works in other games, but not in GMOD. It also records my microphone. So it's definitely something to do with GMOD.

 

[Creepis]

Change the desktop audio device in OBS

 

[rogue]

Change the desktop audio device in OBS

Well I've tried your method and it don't do nothing. Sound works on other games but it doesn't work on GMOD or any other Valve games for some reason.
Anything else?...