I've installed 6 DS7000 systems so far. The homes in our 35 yr. old Phoenix, Az neighborhood are block construction but interior walls are wood frame and sheet rock and the houses are similar in layout and size. However the last 2 systems I installed (which I'm still working on - getting to be a little embarrassing) still have same range problems. I moved the PS561 from the far corner of the house to the approx. center (other homes I've done have the PS561 at far corner and no problems) and I solved the sensor not checking in problem with the windows at opposite end, but now 2 sensors that are in a bathroom but within say 20 ft. are my new problem. I know there could be other factors with maybe stray signals and obstacles in walls that I have no controll over. What I'm wondering is... is the door/window sensor sending a signal to PS561 or is the PS561 transmitting and receiving to make the circuit valid? Could the PS561 be weak with its send/receive circuit?