[Paraview] PV 4.1.0 plot over line question

[Stephen Wornom]

My mesh is unstructured. I want the values along line in the 
x-direction. The line crosses two cylinders.
PV proposes 100 values.
When I edit the .csv file that is created when I "save data", I find  5 
lines with nan. They are near where the cylinders break the line.
Any ideas as to not get the nans as they are in a critical region.
Hope my question is clear,
Stephen