Q. I keep getting #### signs in Excel, no matter how wide I make the column. What is happening?
A. This usually happens when Excel thinks you want to display a negative date or time. Since it is unable to do this, it shows a seemingly endless string of # signs.
Try transposing the calculation so that the later date or time is expressed first (Later Date-Earlier Date). If you were really looking for a negative number of days, you could clear the formatting to see the numeric result.