The error "Minimum data value cannot equal maximum. The scaling data are in the range of 0 to 10e-18." indicates that the difference between the minimum and maximum values does not meet Surfer's requirements. Surfer requires the difference between the minimum data value and maximum data value to be at least 1x10-5 (0.00001).
If your data values vary over a range smaller than 1x10-5, consider using the Data | Data | Transform command to convert your data values into units where the magnitude of the data values is greater than 1x10-5.
Updated September 4, 2020