First time setting up a HT. All appears correct wiring w digital coaxial cable to Sony DVD and other audio and video connections thru receiver. The Dolby Digital 5.1 format (nor DTS) does not seem to work (i.e., the speaker icons on the display do not light up). Used a number of 5.1-friendly DVD's (and a DTS). Got the digital/coax source lit up. Suggestions? I've seen this type of msg on a few other threads (RCA 2500). Is this a known problem w RCA?