04 Ram need radio install help

I have a 2004 Dodge Ram with the Infinity sound system.  I am wanting to replace the stock cd player with an aftermarket one.  I have bought a wiring harness kit to avoid from cutting all the factory wires.  I wired up my new cd player and pluged it in and I get no sound from the speakers.  I have noticed that there is only 4 wires used for the speakers.  I am assuming Dodge uses a common ground on the speakers but I am not sure on this assumption.    Any help would be greatly appreciated.

For 2004 ram that uses the infinity amplifleir you will have to go to amplifier behind the glove box and Bypass it. There is no possible way to turn on  the Factory amp on, since its turned by databus. That is why you  dont have enough wires  at the factory radio plug. Follow this link and read post you will know 

http://www.carsound.com/UBB/ultimatebb.php?ubb=get_topic;f=3;t=002147#000000

Wish I was aware of this before I took my dash all apart.  I bought a "kit" from ABC Wherehouse, they told me "we use these all the time".  Well I see that they are full of bs.  Thank you for the quick response.  I will have to find an amp bypass kit then.  Do you think an Eclipse cd player puts out more amps per speaker than the factory amp? 

fist af all there are 2 types of infinity versions in the type of trucks the u have.

"I just spoke to metra. The 2003 used the 70-6512. In 2004 there is 2 different systems. If the factory amplifierhas one harness. Then the 70-6512 will work. If the amplifier has two harnesses. The 70-6512 will not work. They are working on a new harness.

Last week I did 2 2004 for models one of them had infinity system.