One other observation. The error is a catch-22. First it says you can't leave box B blank. Then, when I put a zero in there to get past the error, the new error says you can't have a number in B with A blank. The problem is A is not allowing a number to be entered. So, I take out the 0 in box B and the original error shows up again.
Lather, rinse, repeat, ...
