cell phone mute

I installed a Nokia Cark91 kit in my car and the mute worked fine with my Sony CDX-M650, but when I hooked it up to an Eclipse CD player using the pink wire, the radio does not mute.  Is it not compatible, or does one take a - signal while the other takes a + signal

The Nokia's CARKIT-91 has a yellow wire that goes to ground when making or recieving a call--- verify this! If so, Kit is OK .If not, you shorted out the mute circuit(replace handfree kit). Eclipse head unit should mute if you touch the pink wire to ground--- verify this!! If mutes radio OK .if not replace head unit or use a relay to interrupt the ACC wire of the radio via the Yellow wire from Nokia kit 91. If both OK the you simply need a relay to boost the ground output coming from the Nokia KitI'm Don.I can answer all your security questions. I have 12 years in the industry.