I had the same problem. If your car is still under warranty, simply go to the dealer and have the keyless entry remotes replaced. If your car is not under warranty and you do not want to fork over the hefty fee for new remotes, you should be able to repair them yourself.
If you open your keyless remotes, you will likely find that the contacts which hold the battery in place have come unsoldered. Basically, the problem lies in the fact that Daimler/Chrysler used a cold soldering method when adhering the battery contact to the circuit board in some of these remotes. Under normal wear, these cold soldered contacts will eventually bust loose.
In order to repair the remote(s), you will need a soldering iron and solder.
1)Remove the screw from the back of the remote. Pry apart the two halves of the remote using a dime or penny.
2)Remove the circuit board, placing it battery side up. Remove the battery.
3)Carefully place the battery holders contact pins back into their respective holes.
4)Take care to put a small amount of solder on each of the loose contact pins. Put a small bead in both the back and front of each contact pin.
5)Replace the battery and put the circuit board back into the remote. Test to make sure the remote is functioning properly, then snap the back of the remote on and replace the screw.
Don't thank me, credit for how to repair this issue goes to 'Sodapop' from custommagnums.com