Tough case to crack! For a refresher, relative to distances from console to sensor, go to post #93 (with image) in this thread about zone #4. Every time (moved the sensor from the right to left or added an antenna) I think I've found a work around, zone four eventually troubles out. Keep in mind though that it is always while the window is open, i.e. the sensor and magnet are not together. The problem with this being I'm going to get a false alarm if the sensor doesn't call home during a four hour period while armed. The offending sensor has been directly across from (but much lower than) the console for four days without a nag, jerry rigged to an air conditioned window. I put a different sensor (still lying horizontally) over at the zone four window and it will eventually trouble. So I now suspect it has to do with the horizontal position as Brian mentioned. I have sensors upstairs on the windows horizontal and downstairs above the doors without a problem so it has to do with just being three inches lower than the console, even though it is in the same room. Hard to believe! I may just get a switch and magnet set from Big Johns for $3. Before I do that I'm going to keep the sensor vertical for several days and see what happens. I can actually arm the window that way by taping the side of the magnet to the side of the upper window but I wouldn't be able to open the top or bottom. I could screw in 1"x 2" on the upper window like I do on the air conditioned one if I am really concerned about securing it. Honestly, at this point I feel I'm going to be more stressed about false alarms than an actual break in!