Hi I have had my MTC for my old Zing (not Zing air) running on my Mac from ages ago. I've just done a update of files for MacOS Sierra 10.12.3. I downloaded the new updated version of MTC from the website, and stupidly erased the old one before the new was working. Asked for registration number and downloaded the activation code (the only one I have ever received) and nothing is working. I can't even cut and paste into it. Help. I know the number is years old. Do I need to buy another registration number?