BRepBuilderAPI_MakeFace

I have a problem with meshing faces built with BRepBuilderAPI_MakeFace:

BRepBuilderAPI_MakeFace MF(S, W);

where S is the underlying Surface and W is the closed Wire that represents
the outer face boundary in 3D space.
If S is a plane everything works fine and I can mesh the face,
but if S is BSpline surface for example, I cannot mesh the face, although
it was built correctly (I checked the error status after face creation).

Does anybody know where the problem is?

Is there a possibilty to assign a parametric description in the domain of the surface
to the edges of the wire (perhaps OpenCASCADE cannot project the 3D boundary onto the surface)?

Thanks

Nicolas