I had the same problem and no one had an answer for it. In my case I bought a new computer and then tried to use my MEP15 from my old computer on it and it told me I wasn't the administrator to use it. I still can't use the MEP15 on the new computer and I was running out of time so I bought the new MEP16 and it works. I'm guessing the software is liecnced to our computers (best guess).
When you install the program you need to register on line to have it activated. If you need to reinstall it on a new computer you will need to contact Magix tech support to have the activation reset before you can use the program.