NXOpen, How to get first and last point3d of a dimension?

Question

I'm trying to get the first and second point of a given dimension in NX draft. Actually I tried this code:

var firstPoint3D = dimension.GetFirstAssociativity().FirstDefinitionPoint;
var SecondPoint3D = dimension.GetSecondAssociativity().FirstDefinitionPoint;

but the result always is 0,0,0 for both.