Hi folks.
I use sumproduct to sum columns of values after testing against 2 criteria.
At first it was working great, and then it stopped working once one cell
that I was testing against had a value in it. It's actually become quite
finicky. It'd work in some cases, but not in others.
My version of sumproduct is:
=sumproduct((Col&RowRange = cell a)*(Col&RowRange = cell
b)*(Col&RowRangeFinal))
Where Col&RowRange would be a column, and range of rows; cell a, and cell b
would be the values that I'm looking for; and the Col&RowRangeFinal would be
the column that I'm summing up.

I have to ask-- would this be affected by cell formatting? (I've gone so far
as to copy and paste cell values from the source regions to the final
regions, and it still only works sometimes.) If so, why? It'd be really nice
to know, so I can ensure consistency, and continuity.
what else would cause this to fail?
Oh, and I did try the comma's instead of *'s as shown in the office
assistant help file. That killed everything with no sign of errors, or #ref,
value, etc....-- i.e., I just got 0.000 for the returned value.

Thus far, aside from this issue, it's been a real godsend, so I'd hate to be
forced to use something else to solve my reasons for using it to begin with.