Attempting to install PDF Fusion using the serial number from the registered products list in one's Corel account causes an error that the "Serial number is invalid".
Causes 1: PD01M22 Prefix is present
An identifier prefix (PD01M22-) is added to the PDF Fusion serial number and should not be entered when installing PDF Fusion.
If your serial number is PD01M22-XXXX-XXXX-XXXXXXXX, enter only the XXXX-XXXX-XXXXXXX portion as your serial number.
Cause 2: Caps Lock is not on
Even though PDF Fusion displays all serial numbers in upper case letters, it does not accept lower case characters in the serial number when one types them in.
CAPS LOCK must be on (or shift being pressed) when entering your serial number for PDF Fusion. If you enter the serial number without caps lock on (or shift being pressed), the serial number will be reported as INVALID.