This is my first post and first time purchasing a radar detector. Anyways, I bought the 1788R from Radio Shack. It seemed to work fine the first day as I did detect several signals, including my own garage door opener everytime I pulled in or out of my garage. I am very inexperienced with detectors so I just left it in "Highway" mode and just drove around to see what would happen. Got some K ad Ka signals, but no X alarms even driving around town. Well, today I drove around some more, and I couldn't get any alarms at all. Finally I found a trailer showing your speed as you go by, and got absolutely nothing. I drove right passed it three feet away several times in all of the modes, and not even a chirp. It didn't even pick up my garage door this morning, which it always did yesterday. The only thing I can think of that I did differently is run it straight from the dash outlet cord without the batteries installed. I did not think this would hurt it, but I am wondering now if it did somehow. Anyone have any ideas?