The ADD button on the Synthesizer tab in Magix Music Maker 16 is no longer available. Using Windows 7 machine and not using Easy Mode. Button was present before since I was able to add several VST's but since the upgrade to 16.05 (newest patch) it seems to have dissappeared.
You did not mention if you are using Windows XP, Vista or Windows 7.
In Windows XP I had faced such problem but rarely.
Here is a screen shot when Easy Mode is turned off add button is displayed.
nihon94
It is strange, did you contact Magix support yet? here users share their experience and answer.
Therefore, it would be better if you could contact magix support and explain about your problem.
nihon94