It is possible that your test did not determine that the cells that look like
numbers are really numbers as far as the the summation formula is concerned.
An easy way to make sure that the numbers are really numbers and not text is to
either multiply the numbers by 1 or add 0 to the numbers. This will convince
excel that the cells are numbers and not text. This is a common problem when
reports from other systems (accounting systems in particular) generate output
in excel format. Your first problem could have a similar genesis. A first
clue that cells that appear to be numeric are not numeric is when they align to
the left. Of course you can align numbers to the left, but that is not usually
the case.

Good luck.

Ken
Norfolk, Va.