[vtkusers] Why doesn't the Delaunay2D->Update() work?

[Terence Lim]

Hi folks,

I am inserting new points into a vtkPoints object, I noticed that after I
insert the point, the corresponding vtkPolyData object is also updated.  The
problem is the when I view the corresponding vtkDelaunay2D object, the
resulting TIN does not contain the points that I have inserted.  I have
tried using Update() but this had no effect.
Any ideas? Here is my code:

points->GetNumberOfPoints();   //outputs 24
polydata->GetNumberOfPoints();//outputs 24

points->InsertNextPoint(coord[3]);    //insert the point

points->GetNumberOfPoints();   //outputs 25
polydata->GetNumberOfPoints();//outputs 25
Delaunay->Update();

PolyDataMapper->SetInput(Delaunay-GetOutput());
etc...

Thanks,

Terence