Perhaps you're "clearing" the cell using the spacebar, which inserts a
space character into the cell.
This may help:
=IF(LEN(TRIM($B45))=0,"",F11+...)
The other factor is that the #VALUE! error indicates you've got text in
your argument cells (F11, R11, ...) which return #VALUE! when used in a
math function.
> have a summary table running using this formula:
> =IF($B45="","",F11+R11+AD11+AP11+BB11+BN11+BZ11); copied down several
[quoted text clipped - 20 lines]
>
> Brian