I've got a Pioneer DV-757Ai DVD player, Sky+ and a Pioneer AX5i amplifier. Both are sending Dolby Digital Signals, the DVD player through FireWire and the Sky+ through SPDIF (optical). The amplifier indicates that it is receiving a Dolby Digital signal, however, all the sound is going to Left and Righ Front speakers, and subwoofer. The Center, Rear Right and Rear Left speakers are not giving out any sound. I went to the speaker setup that the amplifier has built-in and it sent out seperate signals to each speaker including the other three that usually do nothing, and everything worked fine. What's wrong?