How to get full surround out of my motherboard?

Hey Good Folks,

I am having problems getting my new motherboard to marry up tp mt Cambridge Digatel audio processor. I can only get the front speakers and sub to work not the rear. I have set the audio from dig to analog and dig and set it for 6 speakers. still no go. Any ideas? MSI NEO4 SLI new mother. (not he platinum with soundblaster built in)
Thanks

Well as no one had any answers I found a solution. Here it is in case it helps someone else. I bought a 16 dollar AC3 SPDIF cable and used it instead of the seperate hook ups. Sounds great>