Layer.CreateCurve broken in X7 SDK?

We already have X6 integrated into our product. I'm now trying to add X7 functionality, but I'm finding that calls to Layer.CreateCurve is throwing an exception.

Here's a quick sample in C#:

        static void Main(string[] args)

        {

            VGCore.Application cdr = new VGCore.Application();

            VGCore.Document doc = cdr.ActiveDocument;

            doc.Unit = VGCore.cdrUnit.cdrCentimeter;

            VGCore.Curve curve = cdr.CreateCurve(doc);

            VGCore.SubPath spath = curve.CreateSubPath(6,6);

            spath.AppendLineSegment(6, 3);

            spath.AppendCurveSegment(3, 0, 2, 270, 2, 0);

            spath.AppendLineSegment(0, 0);

            spath.AppendLineSegment(0, 9);

            spath.AppendLineSegment(3, 9);

            spath.AppendCurveSegment(6, 6, 2, 0, 2, 90);

            spath.Closed = true;

            VGCore.Shape shape = doc.ActiveLayer.CreateCurve(curve);

        }