Car Stereos: installing 2005 dodge dakota car stereo, panasonic car stereo, purple wire

Question
I've taken the old one out and have tried to get the new panasonic car stereo to run but I can't get power to the radio.  I have the car harness but I can't get the thing to run.  can yiou give me any suggestions?

Answer
I had the same problem with my Dodge Ram.  The computer controls all the components of the truck.  You can buy a wiring harness adapter with a circuit board integrated on it, or you can find a switched wire under the steering column.  Apparently, there is a purple wire under the steering column that is a switched wire and it can be spliced into for your switched power, but I would just buy another wire harness adapter with the circuit board to get the proper wiring setup.  Hope this helps, Scott