[Paraview] Calculated scalar does not display in contour

[Robert Ferrell]

Here's some more precise information about the trouble I have displaying a
calculated scalar field, ScaledTemperature, with a Contour widget.  The
problem seems to be caused by using a Cut.

Here's what fails for me:
1. Read a .vtu mesh file, containing cell field Temperature
2. Filter CellDataToPointData
3. Calculator to compute ScaledTemperature from PointTemperature
4. Cut to display a planar crossection
5. Contour the ScaledTemperature.  I can create the contours, but 
ScaledTemperature does not show up in the Property pull down.  So I can't
color the contours with ScaledTemperature.

If I reverse the order, first contour, then cut, ScaledTemperature shows
up fine.

thanks,
-robert