Cutting x-sections from x-ref'd drawings

If you attempt to cut a cross-section from a x-ref'd
drawing, you will the error message "Contour not found" when
you attempt to click on the contour line.

AutoCAD limits the amount of information we can retrieve
from an x-ref'd drawing. Unfortunately, we cannot retrieve
any polyline information from a drawing that is x-ref'd.
When we try to cut cross-sections from contour lines that
are x-ref'd (i.e., not really contained in the opened
drawing), AutoCAD will report back to RMS that it is not
finding anything there. This is a limitation contained within
AutoCAD.

If this is the case, work on the actual drawing containing
the contour lines, or import the contour lines into the
current drawing.