Why do I have no sound from Bose Cinemate GS Series ll when using optical cable?

I just bought this and it was a cinch to hook up but when I hook up optical cable from Bose to TV I get no sound. Using the standard RCA cables (Red and White) I get sound but with the money I put in I want digital. Note: I am using HDMI for my cable, PS3, and XBOX though that shouldnt matter right?