Illumination wire not affecting Head-unit

I just connected the illumination wire to my Pioneer DEH-8400MP deck.  My dad, who is a technician at a major Dodge Dealership in St. Louis, MO, looked up the wire color for me in the instruction manual, so I know it is the correct wire from the car.  The Hu does not dim when I turn the Headlights on and play with the dimmer switch.  I looked at both fuses (car and HU) and they both LOOK fine.  Should I replace them both and go from there.  Does anyone know why else this shouldn't work.  Maybe a setting in the deck or something

Thanks

Jacob