Errors CHK-8001 and CHK-8003 indicate that your purchase is being declined by our fraud verification checks. Please feel free to confirm you are entering the correct information, and that your PayPal account is verified (requirements for this vary by country and are determined by PayPal) and then try again. Please note that if it doesn't work after a couple of tries, additional attempts will likely also be declined.
This error may be related to the IP address that you are entering the information from. If it isn't identifiable as located near the billing address, the system won't let you update for security reasons