Why an HDMI connection doesn't work on a panasonic viera?

The simplest answer is to check your TV’s remote control and change the input.

My guess would be that the bluray player is transmitting a signal the tv cant show such as full HD (1080p) when the TV is 720p or a something.

Check video setting on TV also ^ ^ ^ . Borrow another HDMI cable could bad.

Welcome @naujda095 ! ! !

It’s possible that “HDCP” is implemented on one of the units but not the other. That’s a copy-protection scheme that works over HDMI. If the disc you’re playing has HDCP on it, and the blue-ray player does too, then the TV has to have it too or the player won’t send the video to the TV.