To start with, you haven't actually used the SUM function. You have given
the function only one argument, and you haven't given it any other arguments
to sum to the first argument. If you want B32-D32 the formula is =B32-D32,
and it doesn't need the SUM function. [If you want to know how the SUM
function works, look it up in Excel help.]

If you want to calculate this only if there is data in both cells, you can
use =IF(COUNT(B32,D32)=2,B32-D32,"")
--
David Biddulph

milt wrote:
I want to SUM two cells in an Excel worksheet but only if there is a
value in both cells. For each month of the year I want to show total
minutes (B32:43) less minutes used (D32:43). The answer will be in
(E32:43). However if I use the simple SUM function =SUM(B32-D32) I
get the total minutes in Column E if there is nothing in column D.
I've looked at SUMIF but cannot figure out how to use it for this
purpose. Thanks for your help.