Help needed - NAD T777 no sound from center and surround

Hi there

help needed here. 
 

just got an used NAD T777 and got it connected excitedly. The front works fine and sounds good. But I just can’t get any sound from the center and surround. I do get testing sound when in testing mode so the connection is fine. Just no sound from any movie. 
 

did I do anything wrong? Got all speaker setting right…

thanks

azmixr