I'm trying to find a way to get a visual alert if a cell should have a number
in it, but doesn't. i.e. one column is for how many files were sent, the
next column is for how many we received back. If we don't enter anything in
the "received back" column, I want to be able to see that at a glance without
having to scroll through a long sheet and possibly missing an empty column.

Thanks so much!