You are probably missing a comma in your "unused' key.

This works:

        DESCRIPTION => {
                ....
            },
        UNUSED => {XlsColumn => -1}
        }
    );
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My print statement works without complaint:

 print  grep ({ $DetailSheet{ColumnName}{$_}{XlsColumn} == 2 } keys %{
+$DetailSheet{ColumnName}} ) ,"\n";
  # Note - grep params are enclosed in parens.
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