The non fader should be going to the rear channels on the amp (3&4) and then bidrge those two channels to the sub. The rear rcas are the ones that should be empty. The rcas for the front should go to channel 1&2 on the amp. When you tried the sub out did you make sure it was turned on in the deck? If you move the front rcas to 3&4 do you get sound out of the sub?