Armada DVD wiring

Anyone know how to tie into the head unit wiring with an after market DVD player?  I tied into the AUX jack but for some reason the rear controls won't select DVD or AUX so I can't use the IR headphones.  I'm thinking you must need the OEM DVD for the controls to select DVD or AUX.  Several other Armada owners have said their rear controls won't select DVD or AUX as well so I'm sure it's not just a bad controller...although I can't get a response from the dealer.....

Here is the wiring diagram for the factory system.

Tied the enable and audio on wires together, spliced into the audio and it works.  Need a pre-amp though (it needs one with the AUX as well).