IsNull Question

Jessica, this looks promising, but when I tried a test, I got the following error:

The data set ‘DataSet1’ contains a definition for the Field ‘DiffExemption’. This field is missing from the returned result set from the data source.
[rsErrorReadingDataSetField] The data set ‘DataSet1’ contains a definition for the Field ‘DiffExemption’. The data extension returned an error during reading the field. There is no data for the field at position 11.

DiffExemption was the field I set up, whose value is set to the following:

=IIF(Fields!TaxAmountOwed.Value - Fields!OriginalTaxAmountOwed.Value = 0,"Zero",Cstr(Fields!TaxAmountOwed.Value - Fields!OriginalTaxAmountOwed.Value))

Do I need to somehow specify the DiffExemption as a column in my query, and if so, how? I tried putting another column in the select list and saying AS DiffExemption to it.  This had the effect of resetting that field to just the value of that column.  I then changed it back to the formula above, but when I run the report, it still displays the value of the column that I assigned to DiffExemption, rather than the value that should be created by the formula...