If your GPS is not connected (it appears red on your collar’s screen), first go outdoors, under the open sky, and make sure the antenna is pointing to the sky. Your SpotOn collar may not connect to GPS if you are indoors, under an overhead structure, if the antenna isn’t facing the sky, or is covered by your hand. See if the GPS letters turn green. 
If they are green, you are good to go! When SpotOn is on your dog, make sure the antenna is always sitting on the back of your dog’s neck and has a clear, unobstructed view of the sky.