[vtkusers] is it possible to get contour surface from Cell data?

[Wat]

Hello all,
      I want to generate a contour surface directly from the cell scalars ( 
not by transfrom the cell data into point data) . Would anyone tell me that 
it is allowed or not?  I try to get this by passing the cell scalar to 
vtkContourFilter  but vtk said that no data was found.

regards
Tirawat Boonyatee