We're sorry to hear these Whitestrips are not sticking to you teeth, after the many quality tests these kits have undergone, this isn't the result we expect. If the strip begins to slip, close your mouth, and create suction to tighten the strip to your teeth again, and make sure your teeth are dry before applying. If you have any questions or would like some further tips, give us a call at (800) 395-8423.