Some possible causes of this error are:
- Using a Customer Number from a different version of Final Draft (for example using a Final Draft 10 (XFDx) number in Final Draft 12, which requires a number that starts with KFDx);
- Not including the dashes -- KFDS-1234-ABCD etc. is correct, KFDS1234ABCD etc. is incorrect;
- Too many attempts -- restart your computer and try again;
- Including an extra space before or after the number when copying and pasting -- be sure you copy only the Customer Number with no extra spaces;
- Using a zero or a one (digits) if typing in the number manually. Customer Numbers don't use 1's or 0's, those are the letters I (as in India) or O (as in Oscar).