IF formula not working =IF(NOT(ISBLANK(M3)),"",IF(ISBLANK(L3),"",TODAY()-L3))

Hope you can help me again. While out of the office, another column was added to my report. I should be able to simply adjust the column references, but it isn't working. All cells come back blank. No errors and no proper results. I am flummoxed. This was working in December. Can't figure out why it won't work now.

=IF(NOT(ISBLANK(M3)),"",IF(ISBLANK(L3),"",TODAY()-L3))

Formula is in cell O3 (Days Pending)
M3 = Resolution Date, may or may not be blank
L3 = Submit Date, may or may not be blank


If Resolution date is blank and submit date is blank, result is blank
If Resolution date is not blank and submit date is not blank, result is blank

If Resolution date is blank, but Submit date has a value, subtract todays date from Submit date to provide the number of days the item has been pending.

Thanks! That seems to have done the trick!!