There doesn't seem to be anything wrong with your formula.
I would advise you to look at the cell properties (Ctrl+1) and make sure they are the same.
Your formula is unneedly long though.
Since you are basically saying if E8>M8 then "Late", anything else (either = or <) "Timely". the formula:
would be enough.
If you are still having problem then it might be an idea to post your workbook using www.speedyshare.com.
Good luck and best regards,