I compared it again (took a copy from the server again where I've put the fixed file yesterday ...)
Yes, both are exactely the same
BUT

Don't ask me why. I've had a look on my gallery just now ... the error messages are gone ...

seems that a miracle occured, doesn't it???
I am even able to log in again.

So everything is OK. I will check it out tomorrow again ... I hope the bloody messages won't be back again.

Thanks Nicky an Jan for your time and support
So lets go on with daily business ...

regards
Tobi