Hello to all!

I am trying meshpy but I have difficulties with basic examples to work - for example this one:
https://github.com/inducer/meshpy/blob/master/examples/demo.py

The code runs OK, but it stops at line:
mesh.write_vtk("test.vtk")

and I get an error:
VtkData.__init__.warning:
    No data defined


I think that vtk is working nicely as all examples from:
http://www.vtk.org/Wiki/VTK/Examples/Python

work without problems.
Could anyone point me in the right direction to look for problems and to fix them?
Thanks for the help!


--
Best regards,
Luka Skrinjar