**This issue has been fixed in ArcGIS 8.1.2**The error message "Failed to evaluate the calculator equation" occurs, when running the SAMPLE function in the Spatial Analyst Raster Calculator.SAMPLE(maskgrid)
This is a known issue with ArcGIS versions previous to 8.1.2. Note that the output ASCII file is in fact written to the current working directory.
In versions previous to 8.1.2, run the SAMPLE function, then navigate to the working directory to see the ASCII file.
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