I would like to ask a question if possible,  I have fitted 4 pir detectors to a pioneer dvr. Power +- from a power point, and a blue wire to nc and a yellow wire to c,  at the dvr input the blue goes to a1 and then so on to a4 the yellow bunched to - ground. I have activated all on the settings but only 1 is activating when we walk past. I would appreciate any help in telling me what I've done wrong as I can't work it out.