I've got a Dish Network receiver hooked up to a DD/DTS receiver via digital optical. What am I doing wrong when DD-encoded material is playing correctly through all 6 of my speakers, but when Dolby Surround or stereo material is being played, it only comes from my left and right speakers, not my center or surrounds. With my old receiver, I remember all vocal material coming thru my center channel, but now with Dolby Surround and regular stereo material, there's nothing from my center speaker. I'm using a JVC HTB now (TH-A5). Any ideas?