Get start and end U param of a circular edge

I have a circular edge:

The edge is not a full circle though. When I evaluate the curve I get a min U and max U as 0 and 2 radian. That makes sense. It is a circular edge. When I do:

Vertex startVertex = (Vertex)edge.GetStartVertex();
Vertex endVertex = (Vertex)edge.GetEndVertex();

I get null for both the start and end vertex of the edge. Why? How do I get the start U and end U of the edge itself rather than the underlying curve?

**EDIT**

The edge highlighted above is the result of a fillet.

The underlying curve is CIRCLE_TYPE = 3002.

Somehow measure can result in a set of X, Y, Z coordinates for the start vertex and end vertex of the edge yet I get a null?

Is this a bug?

How is Measure getting the actual coordinates of the edge derived from a circle type curve?

SolidworksApi/macros