Are you using it in the same location? Indoors GPS is iffy at best, because the satellite signals are very weak, and the frequency is easily blocked. Liquid water will totally block the signals, and you have enough water in your hand to block them entirely. You need to be outside, with a view of the sky, in order to get a good test. Newer receivers can get better reception, since they can use more channels, but they can still be unable to get a signal inside buildings, especially if there is a lot of steel, or the windows have a metallic film.