I have tried to register a few times, have had no problems with my other lenses. I fill out the screen hit enter and I get a error message to call the number and hit 1 for support. The first time I was at work and didnt have the box or lens with me but all the paperwork, was advised to call back with lens and box. did so and thats when they said 831 doesn't appear to be sold yet, had me email them copy of the filled out online form, and scan receipt and serial number card, did so and have had no response yet.