Welcome to the forum, seattlecosmo.
Dave mentioned the first thing that came to mind in terms of the receiver, so I'll poke at the cable and the DVR to start with.
1. Now, this might sound patronizing, but it's not meant to be. On your optical cable, did you remove any plastic or rubber caps that were on the ends? To some, that is obvious. To others, it's just not something that they think about.
2. I'd also suggest disconnecting the optical cable from the Denon, turn on the DVR, and see if there is any light emanating from the end of the cable. Don't stare down the tube, but you should be able to see some light coming out of the ends. If there isn't any light, then no signal is making it to the Denon. If that's the case, we'll pursue this idea further.
Adam