One of Two Raster Surfaces Does Not Show in Spatial Analyst Drop Down List

Discussion created by lrkneupper on Sep 26, 2011
Latest reply on Sep 27, 2011 by lrkneupper
I have a map with two raster surfaces.  In the drop down list for Spatial Analyst only one surface appears for selection.  I can work with that one surface (adding contour lines, etc.) but not the other.  I can find no clue in Help or online documentation as to why this is happening.

Any ideas?