My old home has a mixture of knob and tube, 2-wire, and 3-wire (w/ ground). I replaced an incandescent floodlight with a motion sensing, LED light. The circuit also has another switch in the garage, a garage light, and another incandescent flood flight. Both switches control all three sets of lights. My issue is the LED lights don’t come on at all. I checked that electricity is flowing through the device with a non-contact voltage detector. I used a known good light when I thought my new one was a lemon. Both lights come on when put on a different circuit. Could my old 2-wire system be the cause? Could there be a low voltage situation? I’m unsure about what’s going on as I’m not an electrician.