[Paraview] polygon rendered incorrectly

[Martin Rose]

Greetings,

I have generated a simple vtk file that contains a single polygon. The 
file is shown below.

# vtk DataFile Version 2.0
Output
ASCII
DATASET UNSTRUCTURED_GRID
POINTS 6 float
0.0048265 0.00753943 0
0.0048265 0.00752686 0
0.00485421 0.00752571 0
0.00485266 0.00750789 0
0.00485804 0.00750789 0
0.00485804 0.00753943 0
CELLS 1 7
6 0 1 2 3 4 5
CELL_TYPES 1
7
#end of file


After loading the file in paraview, the surface of the polygon is not 
displayed correctly. It seems that an additional triangle is displayed. 
However, the wireframe is displayed correctly. I have checked the order 
of points and confirmed that the order is correct. I also multiplied the 
coordinates by 100 but the problem persists.

If I add the first  point of the polygon again, the surface is displayed 
correctly. The modified lines read:
CELLS 1 8
7 0 1 2 3 4 5 0

Unfortunately, that fix does not work for other polygons that show the 
same problem.
Is there something wrong with my vtk file?

Greetings,
Martin