thanks for the quick reaction and the question.
At the moment I have a working environment for developing after go back some steps of code generation. Maybe restarting my machine helps either.
I want to find out, what the reason was. It's a little bit difficult, because I have no idea what the crucial step was. The problems began at the moment where I changed properties of the field and chose 'text' for the db-typ.
I would just like to know what cliff I must circumnavigate.