How to fix 2007 VW Polo Gti Front Passenger window?

Hi,

I desperately need some help with the front passenger electric window. Here's the fault;

The window does not function at all when the button is pressed. It doesnt even make a sound when pressed. When the door pad is taken off and the control unit for the window motor is disconnected, and reconnected again, the window functions normally. As soon as the ignition is switched off, or if the car is driven for a short distance, the window stops functioning again. What i do know is, the fault can't be the window motor or control unit because a new motor and control unit was tried, and the same problem occurs.

Any help or advice would be greatly appreciated