TM-D8000 dead channel?

[Trauma]

Hello
I bought a TM-D8000
On channel 6, the signal light and Meterbridge responds to sound, but no sound is coming out of the speakers.

Any ideas?

 

[Markus Franz]

Don´t know, if you are still reading here...
Maybe channel 6 is in grouped and the group-fader isn´t raised?