Why can't I register Harmony 11?

I have tried to register my copy of Harmony 11 and all I get is a message “Invalid Activation ID - Key Already In Use”

What am I doing wrong?

If you purchased online it should already be registered to your account. If you are unsure, email licenser@toonboom.com and they should be able to help you get the software registered.

I received my update as part of my maintenance subscription so technically I got it online but the original purchase was through direct phone contact through their sales office. The reason I ask as the serial number does not show up on my account and, as I mentioned, I can’t seem to register the serial number I was given. I will contact them through the email you posted and see if I can resolve this. Thank you.