foamToVTK produces illegal (binary) files

fineMesh.tgz

I did

• lid driven cavity

• in setSet: cellSet c0 new labelToCell ( 10 12 5) cellSet c1 new cellToCell c0 cellSet c1 invert

• foamToVTK -cellSet c0

• foamToVTK -cellSet c1

and VTK/c0_0.vtk is unreadable. c1_0 is fine.