put it on radio and see if you have sound. make sure that all the wires are plugged in correctly including the remote wires (usually blue) even if you don't have an amp. If it still doesn't work but you have power it isn't grounded properly. Most likely does need to be grounded again to a parking brake. Might need to install a switch to make it work properly.

 

I had the same problem you described when I put in my new radio. There is an internal amp that must have 12v, or you will have no sound. There is more than likely a wireon your new radio that is made to turn on an amplifier or sub woofer amp. Most of them are blue. This wire needs to be hooked up to the wire that jakebrake mentioned above.

This basicaly sends 12v to a realy and turns on the premium sound system that Dodge puts in the dash. Buy the wiring harness it is worth the extra $10. It has all of the wires labeled for ya.