This might be a long post so I apoligze and bear with me because I am in desperate need of some help!!
Basics:
1995 A6 Sedan
What I am attempting to do (and did) install an aftermarket head unit (Kenwood Model# mp335)
Wiring Harness's Used:
Metra 70-1784
http://www.audiooutfitter.com/70-1784/metra/p70093.html

A second harness ( I can find the model number) it is an Audi/VW amp bypass harness which has the speaker wires corresponding as such and a black ground wire.

Antenna adapter

My issue:
I spoke with a guy at a local car audio shop who sold me the the harness's and he knew and was familiar with what I was trying to do he said the wiring harness's will do everything I need to do. So he walked me through how to wiring everything:
I said the 70-1784 has the speaker wires and the Red, Yellow, Black to power the headunit. The Red, Yellow, and Black will be the only ones used, everything else will be taped off and not used.
The second harness has one wire for each speaker and a black (ground) wire. So I wired the Positive (+) speaker wires from the Kenwood unit to the corresponding wiring on harness and left the black ground wire alone and did not wire that to anything. My headunit gets power but I have nothing coming out of the speakers, the Antenna adapter is conected properly and the headunit settings are setup correct, I get nothing out of the speakers to snap, crackle, pop or sound for that matter. I tried grounding the black wire to the car, and to a negative speaker wire, neither of these worked. The second harness also has a wire for amp power that needs to be installed to the actual harness which i did and connects to a corresponding wire on the Kenwood harness, still nothing.

If anyone can provide some help with this it would be greatly appreciated!

Thank You!