[vtkusers] vtkPolyDataConnectivityFilter: why doesn't this work?

[Terence Lim]

Hi,

I would like to extract region which are connected to certain cells but I
seem to be doing something wrong because I couldn't extract any regions.
Here is my code:

vtkPolyDataConnectivityFilter *connect =
vtkPolyDataConnectivityFilter::New();
connect->SetInput(Delaunay->GetOutput());	<-----this is a polydata set, a
mesh
connect->SetExtractionModeToCellSeededRegions();
connect->InitializeSeedList();
connect->AddSeed(0);			<----------cell id is 0, which exist in the inputted
mesh
connect->AddSeed(2);			<----------cell id is 2, which exist in the inputted
mesh

cout<<connect->GetNumberOfExtractedRegions();  <--- gives me 0?!

Any ideas?

Thanks,

Terence Lim