Mine used to work. I've been messing around with it for days and have been searching the net for info. I had the sensors out and apart, everything looks good and is clean. I've used natural light, artificial light , LED lights, diffusers on, off. shot bullets, arrows rubber bands, pellets. nothing registers. I read the manual, went through the functions to turn the sensors off and on again, new battery. Just doesn't work. However they are no longer in business. BBB report has 3 major complaints where people have lost money and in one instance a guy sent his unit in and hasn't got a reply as to where it is. I would hate for anyone to purchase one of these and find out later they are out of luck.