Assuming you verified install in Device Manager, I see three possibilities right now...
1) You plugged the speaker cables into the wrong jacks...considering how they are gold instead of color-coded, this has happened to me a couple of times with my ZS.
2) Cables are not fully seated into the jacks
3) Card is dead
Something to try is to launch a movie in surround mode, then plug your headphones into each output of the card...if you get no sound, it's possibility #3.