"you have entered an upgraded key. Please confirm it with the key from the previous version"

I just have bought a update version from parallels desktop 12 to 13 as suggested in my software but when i will put the key i have received the message "you have entered an upgraded key. Please confirm it with the key from the previous version" requeste my previous key that I put and receive always the message "The product key of a previous version of Parallels Desktop has been not accepted on the license server". How can I validate it?