You're welcome. Thanks for the feedback!

--
Biff
Microsoft Excel MVP


"EMW103" wrote in message
...
That was it: it was that R59 and S59 both contained formulas, and R
contained
a formula blank, so having changed "" to "0", it now works. Thanks!

"T. Valko" wrote:

What does "doesn't work" mean?

Do you get a #VALUE! error? Do cells R59, S59 contain formulas that might
return formula blanks?

Try this:

=IF(ISNUMBER(T59), SUM(R59,S59))

You haven't defined a value_if_false argument for when T59 does not
contain
a number so the result will default to FALSE.

--
Biff
Microsoft Excel MVP


"EMW103" wrote in message
...
Why doesn't this work, please:
=IF(ISNUMBER(T59), R59+S59). I.e., if there is a number in cell T59, I
would like cell U59 to be the sum of cells R59 and S59.