Passat (B5) :: Window Won't Go Down When Button Pressed But Machine Works

Last Saturday it worked because i left all 4 windows down while driving. On Sunday I drove in the rain, so all my windows were up. The next day on a clear day I put my windows down and noticed the left rear window won't go down but I can hear the normal 'shoosh' sound like the motor works but it won't slide down. I put my hand against the window to push down and it went down (because I had already push the button down so it allowed the window to be opened) When I pushed the button up to go up, it goes up.

To make sure my window can't be slided down with hand by carjackers, I first tried by using my hand to slide down, it won't go down. So it seems like the motor works. When I pressed the bottom to go up, it goes up but it won't go down when pressed down.

Car year is 1999....