Conversion of curves and surfaces to BSpline

Hello,

I need to convert all curves and surfaces of my Shape into max 3 degree polynomial BSpline's.

I try to use follwoing construction:

TopoDS_Shape Shape1;
Reader.TransferRoots();
Shape1 = Reader.OneShape();

const Handle(ShapeCustom_RestrictionParameters) aParameters;
aParameters->ConvertBezierSurf();
aParameters->ConvertConicalSurf();
aParameters->ConvertCurve2d();
aParameters->ConvertCurve3d();

aParameters->GMaxDegree();
aParameters->GMaxSeg();

m_Shape = ShapeCustom::BSplineRestriction (Shape1, 0.00001, 0.00001, 3, 60, GeomAbs_Shape::GeomAbs_C2, GeomAbs_Shape::GeomAbs_C2, TRUE, TRUE, aParameters );

but this example crashed in ShapeCustom::BSplineRestriction.
What's may be wrong and what else shell I use to aproach this requirements?

Thank's in addvance.
Alex