EDIT: I've downloaded the latest version I bought from the My Account page and managed to activate it.
Please ignore the following request.

I bought MAGIX Video 2015 on Windows (ord.# 20141025006361363MXC) years ago (download version), then upgraded to Magix Video DeLuxe Plus 2017 (download version, I have the invoice) and I've been using it on Win 10 and 11 up to last week with no problems. Now I've got a new PC, so I deactivated the license on the old one, downloaded the current Plus 2017 version from your website, and installed Magix Video DeLuxe Plus 2017 on the new one, but it does not work giving a "-14" error (this activation code is not valid or it refers to another product). So I uninstalled the Plus 2017 version from the new PC and installed the old 2015 version and that activated and worked well. But now I have an old program despite having bought a more recent one. So I tried again to install the Plus 2017 version over a 2015-activated one, but there's no way: same -14 error. How can I solve this problem? Many thanks in advance for your help.