if you tint your rear windscreen it will block certain amount of light. so the sensor wont detect and activate the anti-glare function. i notice this after the 1st time install tint. on certain condition when the car is near and the headlight is bright it will activate them. before tinted, car's from far away also the sensor will activate. hope u get what i mean.

It works with TWO sensors. One at the front (facing you and the rear windscreen), and one at the back (facing the front windscreen).

The sensor at the back is to detect whether it is day or night (bright or dark). The one in front is to detect whether there is any bright glare. You will need two sensors because during the day time, if only the front sensor is activated then your rear view mirror will be blue-green the whole day!

A simple way to test it is to do it during daytime on a bright sunny day. Cover back sensor (to simulate "night time" ) and then watch the screen turn blue-green.

One thing I dislike about the automatic review mirror is that when the sun is glaring at the back it won't get activated  . I had to use finger/paper/tape to cover the back sensor (aka "cheat it") so that my eyes won't get destroyed. I just hope they add a feature to "force on" the anti-glare