AutoCAD Inventor :: How To Get Sketch Point Data From Sketch Entity

I was trying to query some sketch points data from a profile Path using code as below. However the program stopped without telling the reason.

Code below:
i = 0;
foreach (ProfileEntity oSourceProfileEntity in oProfilePath) { switch (oProfilePath[i].SketchEntity.Type) { case ObjectTypeEnum.kSketchArcObject: { SketchArc srcSkArc = default(SketchArc); srcSkArc = (SketchArc) oSourceProfileEntity.SketchEntity; // error points[i] = srcSkArc.StartSketchPoint.Geometry; break; } default: { SketchLine srcSkLine = default(SketchLine); srcSkLine =(SketchLine) oProfilePath[i].SketchEntity; // error points[i] = srcSkLine.StartSketchPoint.Geometry; break; } } i++; }