2001 Expedition, no sound from box

Recently installed system. Used a sony head unit, pyramid 2400w amp and speaker box w 2 12: kicker speakers. I cannot get sound from the box. Radio plays both FM and CD's thru fatory speakers only. I have 12v power at the amp, green amp light on. I have changed the amp, head unit and had the box hooked to my sons car and it works. Wiring to the head unit is thru an adapter made for installing afterunit head units and color codes are correct (wiring ). I'm at a loss as to what to check for next. Any ideas?

did you check your rca? are they good? thats the only thing i can think about since your amp is turned on and theres nothing coming out of it did the amp work in the other car?i know some stuff and what i dont know ill make it up feel free to ask