Apple TV2: HDMI Audio not working

I know this is a very common problem everyone is facing, and I also tryed everything suggested here: http://support.apple.com/kb/TS2090 and here: http://support.apple.com/kb/TS2090?viewlocale=en_US&locale=en_US ... Nothing worked.

I'm using an Onkyo receiver device, is there a chance they aren't compatible?

Or is this a faulty unit?