Hoping for some advice and please note I am not an electrician I am just trying to troubleshoot a problem before calling one. I have two pairs of ax130 tn sensors operating lights in an outdoor domestic setting. My question is when I take the covers of the sensors what should I see as far as led lights are concerned. I have a sensor that has no light on it unless the beam is broken, it then turns red. The other sensors seem to have either a permanent red or green light on. Which is correct and can you suggest a way to troubleshoot the sensors to find out if I have a faulty one? Thank you in advance.