Prox might be a little tough to grasp so I have provided a tutorial video that guides you through everything you need to know:
Tips to make it work:
Swipe close and slowly across the proximity sensor to make sure you hit it
When tilting the phone, if you do it with a sudden jerk, it can tweak out the accelerometer and activate a different one. Get the phone in the desired position and then wait for a nanosecond, and then swipe.