Configuring Sound for 5.1

Hello,

I recently bought a 5.1 surround sound set, Logitech Z506. Whenever I try to configure the sound, I only hear the bass and front speakers.
When it's testing for the rear speakers and subwoofer all the sound comes through the 2 front speakers.
I know the set isn't damaged or anything like that, since I tested it in the store first. I have a 7.1 audio card from Icidu so it should work fine.
I'd like to know what to do to get it working! My audio card has the newest drivers and the surround sound set doesn't require any drivers.

I have the jacks on the right places.

I deinstalled Realtek Audio Manager and High Definition Audio Device from my built in audio but still only 2 speakers work.

Yes. I tried through the audio software:
(luidsprekers is speakers
and through sound in the configuration screen:

I disabled the sound in the BIOS as well and i reinstalled my drivers. My subwoofer works fine when I test it at configuration, but it does not play music whenever I listen to something. My rear speakers are still totally dead, except for a really soft noise.

Sorry for my broken english, I'm doing my best

It wasn't, but since it was the standard audio device it worked anyways. i selected it but it doesn't seem to change anything.