no sound from rear speakers in grand am

i searched and couldnt find anything. switched the aftermarket stereo to a newer one and i cant get the rear speakers to make a sound. they were working fine with the previous stereo. i have checked all the wires at least ten times. i tested the new stereo and it aint the stereo. its from the back of the plug to the speakers is where the problem is. any help?

forgot to add its a 2000 pontiac grand am

Is there possibly a factory installed amplifier powering the rear speakers?  If there is  a power antenna wire listed for your vehicle, connect it to the Blue/White wire of your aftermarket radio.

i searched for a amp and couldnt come up with anything. how would i know for sure?

No amp

Make sure that you have the correct rear speaker wires hooked up. Use a 9 volt battery to pop the wires. The rear speaker wires are Dark Brown = LR+, Yellow + LR-, Dark Blue = RR+, Light Blue = RR-. Connect the battery terminals to each wire (yellow to neg and brown to positive). If you have the correct wires and they are connected to the speakers, the speakers will pop. Hopefully you have used an adaptor plug rather than cutting off the original radio plug.sparky