oui oui.

now check:

-your remote wire is pinched or cut off along the way to the trunk
-your remote wire isnt connected to the harness right
-your harness could have the remote wire connection loose
-your HU is the cause of the problem.

i would start by pulling your headunit out. take a spare wire, run it from the harness' remote wire (antenna), and back to the amp. if it works that way...you know its not the HU, but the wire itself.