Error code -14 means during a MAGIX product activation that you're putting a valid MAGIX serial number into the wrong MAGIX product or version/edition.
Which version of PC Check & Tuning is the serial number for? The image indicates you are trying to put the serial number into PC Check & Tuning 2021.
Please use any image editor you have installed - Windows Paint will do - to crop images so that it are legible. The the excess space makes the image very difficult to read - see image below
Thanks for the answer, but still the problem is not solved. In March 2021, I installed this version and everything worked normally until recently. What do I have to do to make it work?
Did you actually purchase PC Check & Tuning? Do you have a serial number for it? Or did you just happen to download and install it when you installed another program, like Vegas Movie Studio (I can see this under your image). As already mentioned, it looks to me like you are trying to input the serial number for a different program.