Arcam AVR300 problem

My amp seems to have dificulty reading the audio signal coming from the DVD player. I'm running a digital cable only, but the amp reads it as analogue so I get no sound. It used to work fine so the set-up is fine. It used to try to switch back and forth, but now I get nothing.

Has anyone else had this trouble and know how to deal with it? Arcam hasn't returned my email yet so I thought I'd try you guys. Any ideas or possible solutions?

Thanks -
Matthew