I just purchased a used ipad from ebay. When I inserted my new att sim card for it and turned ipad on a msg popped up the says "waiting for activation. This may take some time" Nothing happens, as far as the activation after that. I have gone into settings. The ipad recognizes that there is a sim card but that is it. I am not able to add data in order to use the 3g service. Any suggestions? Am I missing something?