I Use OCC 6.3.1.
Only to inform oder users with the same problem.
To build the intersection of different shapes with a plane i have tried to use BRepAlgoAPI_Section. There was rarely a result in an intersection of a simple cylinder with a plane (gp_pln or face) - useless.
The solution is to use BRepAlgo_Section instead. This method is delivering results.
Facit: use BRepAlgo_Section instead of BRepAlgoAPI_Section.