Ever since I got my GWF-1000, it would only sync if put in a window in a room off the back of my house that is almost entirely windows. When I got my MTG-1500, it showed up having synched while in the box in shipping. It syncs every night on my dresser without fail. I've left the GWF next to it for a couple weeks now and it still didn't sync. Well, the last 2 nights, the GWF has synched on the dresser. I guess it learned that it should be able to sync anywhere.