Empire Strikes Back-no center voice track??
 

I just hooked up Sherwood 6.1 digital receiver RD 7108. (great deal-paid $93 new!). Anyway, I am using an Apex AD-800 DVD player w/built in decoder. Tested my hook up w/Empire strikes back in dolby digital EX (auto detected the sound source). The center speaker produced no voice track-just backround sound. Still fiddling with the 6.1 features, would the Apex cause a problem because of the decoder? It's hooked up thru digital coaxl if that helps.

Do I need a new DVD player? I love the Apex, but have to admit the audio set up features very complex!

I had an Apex player for a while, though I didn't have audio problems, I had constant issues with it not playing certain discs. So, I'd be inclined to start your troubleshooting with the player.

I bought a new Sony five discer and it's been smooth so far.

Run your test tones from the receiver first to make sure that the center is working, then make sure you are in the right mode for passing the audio signal and not dolby 2.0 etc. If your center runs with the test tones then I would suggest the player is defective.

perhaps you have the front center and rear center reversed?