HI, thank both of you for your help. Interestingly enough, the solution is a mixture of both your advices:

I had to add the directory to the security setting for writable/readable files AND I have to use the complete path when saving or reading.

But to be honest,I don know why it works this way when it already should have worked the other way. The working directory [ currentdir(kernelopts(homedir)) ] IS the correct one already... so normally no need to add the complete path...

Thank you! Kind regards

Udo