Audio Systems: amps not turning on, rockford fosgate amps, terminal lugs

Question
I have a alpine head unit and two rockford fosgate amps, one for the subs one for the speakers. With the truck running or in accessory, with the radio turned off I get proper voltate all the way to the amps. When I turn the radio on I lose voltage to the amps, all the way back to the terminal lugs. The fuses are good. Anywhere I can stick my voltmeter on the line it doesn't matter, I lose power as soon as my radio is turned on. The remote lines are getting proper power.  

Answer
First off I don't know if everything was ok before so I assume it was.
I also assume you have the leads going to the correct terminals, (+30 to fused connection on the car battery, earth to chassis locally and +15 acc to the signal wire from the radio).
Does the problem persist if all the speaker wires are disconnected? If so, it's NOT a possible speaker wire or speaker coils short.
Disconnect the signal wire from the amp leaving the +30 and the earth, use a short wire and touch +30 to +15 acc terminals on the amp, does the amp come on? if so the problem lies in the +15 acc signal from the radio, if not, the amp is faulty.
Good luck, Peter