Why ca't I register my Audiobox USB?

I have created an account today, mainly because I am considering to buy Studio One 3 Pro.

Since some years ago I have an Audiobox USB that I still use sometimes.

Now, when trying to register that product, inserting the serial number that is said to be on a tag on the under side (U208090150) it is not accepted.

What is wrong? Can you help, please?