@detlef-jockheck ,
Unfortunately, I don’t think you’ve given people enough to go on.
I personally don’t use the installer options, and I’m not currently at a location where I could use the installer to test it out, so I can’t give anything specific. But some general debugging questions:
You say “sometimes”. Do you have any hints as to when those “sometimes” are? Are you doing this installation on multiple machines, and N% of those installations are doing nothing? Or are you running the installer multiple times on the same machine, expecting it to either install or uninstall, and N% of those attempts, it doesn’t do what you expect?