The problem is solved. It was the layout of the pgn-file:

Games in a pgn-file wich are formated in the short-form (e.g.: 1.e4 e5 2. ...) will work correctly. The long form (e.g. 1.e2-e4 e7-e5 2. ...) don't work in the right way.

So it's a good workaround to convert the pgn-file before importing it into eboard.

Ciao jukey