Power window puzzle

[ORAZNC]

I recently picked up an '06 Liberty and I bought it with the understanding it had a bad regulator on the rear passenger side, it rolls down but not up. Bought a new regulator and it does the same thing, even before it is installed. I tested the switch function and it has power at the motor plug in in both the up and down positions. Any ideas why it will not roll up? Window slides easily along guides so there's no binding going on. Thanks in advance for the input!