Missing channels from Creative Blaster X-Fi 5.1 via S/PDIF optical cable

Hi, in Windows 7, when I test the Creative Blaster X-Fi Surround 5.1 Pro, I only hear the front left and right speakers. Center, subwoofer and rear speakers make no sound but I can see levels in the Windows Volume Mixer. I have tried different modes on my Onkyo TX-NR414 (all ch stereo, direct, theater, PLII, etc.) to no avail. All of the speakers are connected properly because I can hear a test of the Windows default beep and other sounds on all speakers.

Thanks for any assistance on this problem.