Upconversion is routing signal from lower quality connections to one of higher quality. So, Component -> HDMI, S-video -> Component, Composite -> HDMI, etc. are examples of upconversion.
Upscaling is changing the format of a signal from lower resolution to higher. So, 480i -> 480p, 480i -> 1080i, 720p -> 1080i, etc. are examples of upscaling.
Your receiver will only upconvert, not upscale.
I suspect your TV does not accept 480i signals on the HDMI input. Look into the manual for specs. To test this easily, set your DVD player to progressive mode. If you get video, you have your culpret. I had the same problem on my Panny and that is what the problem turned out to be...
Of course, this argument presumes that settings and connections are correctly configured.
