Convert a surface mesh to a volumetric mesh in 3D Slicer

Dear Andras,
I used segment mesher. It is generating surface mesh instead of volumetric mesh. I used segment editor for segmenting tumor and brain. then I switched to segment mesher. It always generate surface mesh. I opened the *.vtk file of the generated model into paraview but dont see a volumetric mesh.

Please see the screen shot.

Does segmentmesher do not produce volumetric mesh? if yes what am I doing wrong? would you please correct me?

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