【MSCE C#】CreateDgnRuledSweep无法创建出实体

老师,你好!

请问一下我用CreateDgnRuledSweep与DraftingElementSchema.ToElement为什么创建不出来实体?程序会报错,请帮忙看看怎么回事?

程序代码:

public static void HelloWorld(string unparsed)
    {
        Bentley.DgnPlatformNET.DgnModel dgnModel = Bentley.MstnPlatformNET.Session.Instance.GetActiveDgnModel();
        ComplexShapeElement shapeElement2 = dgnModel.FindElementById((Bentley.DgnPlatformNET.ElementId)1435L) as Bentley.DgnPlatformNET.Elements.ComplexShapeElement;
        ComplexShapeElement shapeElement3 = dgnModel.FindElementById((Bentley.DgnPlatformNET.ElementId)1471L) as Bentley.DgnPlatformNET.Elements.ComplexShapeElement;

        List<CurveVector> curveVectors = new List<Bentley.GeometryNET.CurveVector>();
        curveVectors.Add(shapeElement2.GetCurveVector());
        curveVectors.Add(shapeElement3.GetCurveVector());

        DgnRuledSweepDetail sweepDetail = new DgnRuledSweepDetail(curveVectors, true);
        var solidPrimitive = SolidPrimitive.CreateDgnRuledSweep(sweepDetail);
        DisplayableElement element = (DisplayableElement)DraftingElementSchema.ToElement(dgnModel, solidPrimitive, null);
        element.AddToModel();
    }

测试文件:

扫略模型-问题.dgn