2012 VN 780 No stereo in bunk

Hello all...

I have a new Volvo 780. The truck has the 4 speakers in the front, and the 4 in the bunk. The 4 up front work fine, but none of the speakers in the bunk will work. The head unit is set to play on all 4 channels, but switching it to 2 channels only turns the door speakers off. I checked behind the speaker grills in the bunk, and the speakers were installed and wired. The volume control on the sleeper panel doesn't do anything. Any ideas? Thanks

 

I've done some poking around in the truck. There is no subwoofer in the truck, but I still have not been able to find out what is wrong. If I set the fader all the way to the rear, you only hear sound in the doors, and all the way to the front you hear out of the dash. According to the "fabulous" owner's manual, the control in the bunk adjusts the volume for the rear speakers, but it doesn't change anything. Also, I haven't been able to find the amplifier that runs the rear speakers either

 

Pablo, in the fuse panel in the dash, there is a fuse installed for the amplifier, and i checked with a test light and it is in fact powered. Any other ideas on where this amp is located?

 

There is no amplifier in the upper right cabinet...nor is there a subwoofer under the bunk....Thats what has me at a loss. The truck is fused with the 25 amp fuse which according to the panel diagram, means there is an amplifier, but its not in the normal spot if it has one. There is no wire harness that even goes into that cabinet.