I just recently bought a Pioneer VSX-D509S receiver and I can't seem to get DD5.1 out of it. I have an optical cable plugged into the DVD output and receiver input. I'm just starting out and a bit confused. I read the instruction booklet and it says "DD or DTS is automatically detected and lights up in the front panel" but it doesn't. I have a really cheap RCA optical cable and I don't know if that's the problem or what. Any help is greatly appreciated.