Thanks for the reply and suggestion from PajamaGuy and jtykal. I had been adjusting and sitting in that bathroom for nearly an hour. The motion sensor is just not responding once it is turned on. I even put 2 in there to test it out and it just won't detect. However, once it goes dark, 8 sec. later, it will turn the light back on. It let me to conclude that once a dark room turn into a very bright room, the sensor no longer can sense anything unless it is dark again. In the dark bathroom, a slight movement will trigger the on switch. However, in a lighted bathroom, even major movement (waving arm, walking back and forward and the sensor is at 45 degree) will not trigger it. Somehow, anyone in that bright room become background noise. I put the same sensor in my office, set it up for 2 minute and I can see it check every 8 second (with minor movement I can see the red light blink). I am planning to setup 2 sensor for this bathroom. One inside (set for 30 minutes) and one outside (set for 2 minutes). When I walk in the bathroom, it will trigger the 30 minutes one, then as I walk outside it will trigger the 2 minutes one which will turn off the light in 2 minute. Will that work? I really don't want to do the above step because if someone pass through the 2nd sensor, it will turn off the light in the bathroom while someone is in there. Any suggestion is appreciated! Thanks in advance.