passenger door power lock not working

I've got a 99 Silverado with a rather odd problem in that the power lock wont work on the passenger door but the drivers door works fine.The lock button itself will lock/unlock the drivers door but not its own so I started to search out the spot where the power is dropped.The solonoid wires have power on the lock side but not the unlock and when I tried to use an outside 12vdc source I couldn't get the lock solonoid to work but I may not be doing it right so I still dont know if there's a problem with it or not.As far as I can tell there's no break in the wires where they pass through the door as I tested them with my ohm meter and I'm not sure what else to look for.Can anyone shed some light on this for me?

The lock on the passenger door on my silverado quit working and it turned out that the gears inside the actuator were all mashed up because they are only plastic. When you lock and unlock the doors, listen carefuly if you can hear the motor in the actuator running or not.