Display of warning message

To best describe or illustrate your problem you would be better off attaching a dummy workbook, the workbook should contain the same structure and some dummy data of the same type as the type you have in your real workbook - so, if a cell contains numbers & letters in this format abc-123 then that should be reflected in the dummy workbook. Don't upload a picture when you have a workbook question. None of us is inclined to recreate your data. Upload the workbook and manually add an 'after' situation so that we can see what you expect. In addition clearly explain how you get the results..
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Why not just use Conditional Formatting to highlight the negative values? I think you mean C32 to N32