Shame on me ...

You were absolute right!
Naturally, I did read the 'things that can go wrong'-section, but since 
the error looked completely different than what happened on my system, I 
did not try that out. I should have, of course. There is the solution, 
right in front of my nose, and I'm ignoring it ...

I'm really sorry to have bothered you with that!
Anyway, thanks a lot for your help! I wished that some commercial 
libraries would provide such a quick and patient support ...!

Greetings,
Redge