Scrievener won't accept serial number

My old computer started dying so I recently deactivated my old version and now wish to register it on my new computer. Unfortunately, it won’t seem to accept my serial number. Anything I’m doing wrong?

Thank you!

Which version did you have on your old computer? Was it version 2? I presume you’ve downloaded from the Lit&Lat site to install on your new computer, so it’ll be version 3.1.2. In that’s the case you’ll need to pay the upgrade fee and get a new serial number, or scroll down to the bottom of … s?os=macOS and download 2.9 from there.