As you're installing the product, make sure that you type all the zeros as the number 0 not the letter; there is no letter O in any valid serial numbers. Also, make sure that you have no extra spaces or return characters, just the serial number.

If you're working with our web-based serial number checkers, watch for those errors and watch also that you have all the other required fields filled in. The most common reason for serial number rejections, by far, is for lack of filling in the name, phone, or email fields.