Can't hear CSS gun sounds

Hey Facepunchers

I am having some problems, I have gmod on account and css on another (it got vac banned when it got hijacked).
So I wanted to get the CSS models/materials/sounds etc into my gmod on my other account so I follow the tutorial on the gmod wiki, but I have one problem:
I can’t hear the sound of the CSS guns when I fire them, though I can hear other people shoot.

Can anyone tell me how to fix this?