I see a lot of complaining about false triggers with these sensors. Most of the time it is the fact that people do not realize what kind of "viewing" range these things have. I had one in a position to monitor the driveway and was receiving a lot of false triggers, I finally realized that it was "seeing" my neighbors driveway also more that 80 feet away!
I solved most of my problem by mounting the sensor about 8 feet high on a cheepie web cam mount that allowed me to tilt it down to lower the field of view and adjust it left and right to achieve only the coverage I needed.
Plants and sudden temp changes will trigger these things, so consider that when aiming.
A lot of trial and error but that is why I consider it a "hobby" :)