>I'm embarrassed. It's my fault, I'd overlooked the fact that there is a very large negative number in there, and besides - it's accounting stuff - the sum is supposed to be zero.
>
>Sorry guys, and thank's.
>
>Peter

Good it worked! I had another just an opposite problem before - two sums were supposed to be the same, but they weren't. I was trying to blame it on rounding, but in fact there were some other factors involved I didn't originally taken into account.