S/PDIF Cable not recognizing as connected

[MarkN]

I've been endeavoring to hook up a surround sound system to my desktop for quite some time, and because of how the standard analog cable array works, I can't get 5.1 sound without the S/PDIF cable hookup. I just went to the store and bought a 6' cord, unplugged all the other audio cords, put in the S/PDIF cable, and found that the computer did not recognize that there was any audio devices connected. The output jack is showing a red light, which I understand to mean that all is well, and I tried checking the drivers to no avail.
I filled out my system specs to the best of my ability, but I also found this link, which is the exact model of computer I have, and the only modification was replacing a slightly faulty power source
ASUS Essentio CG5275-AR003 Desktop PC Intel Core i5 650 (3.20GHz) 8GB DDR3 1TB HDD Windows 7 Home Premium 64-bit - Newegg.com

 

[fireberd]

Exactly what do you have for a speaker system? What input is required for the speaker system?

If you connect an S/PDIF cable, you may have to manually set it as the default playback device (??) Windows will only allow one default audio playback device.

Finally, not all S/PDIF's are 5.1. Many are only 2 channel stereo.

 

[MarkN]

Connecting to a Sony... Digital Audio Control Center. Not seeing a moden number on the front, might be on the bottom but it's in an entertainment center right now. The issue I'm having is that when I plug it in, Windows is unaware that it's been plugged in. The red light in the desktop slow is showing, and the cord is showing the red light on the end that plugs into the receiver, so I don't think the cord is the issue. It's just that Windows isn't recognizing the device as active.

 

[fireberd]

Have you tried either enabling the S/PDIF and/or making it the default audio playback device.

Control Panel/Hardware and Sound and finally the Sound Panel, playback section.

Here is my Playback Section.

 

[MarkN]

Ok so yeah, that definitely fixed my output issue, which is embarrassing, because I never had disabled those devices to begin with. Now much to my confusion the output is operating fine, and the receiver just isn't playing any sound from the optical. It'll play Aux input just fine, and I've cycled the input modes to no luck, but that might be a question for a different forum,