You don't need the IF function. You could use =D4-C4+(C4D4)

But I don't know why you're getting the report of resource problems with
that particular formula. That error message is usually associated with
large array formulae:
http://support.microsoft.com/kb/166342.
--
David Biddulph

"squack21" wrote in message
...
This formula gives me a error message every time I enter something in the
worksheet: =D4-C4+IF(C4D4,1). It says Excel ran out of recourses and the
formula could not be evaluated. Originally I was lookin for a formula
that
would calculate minutes of production time per shift. AM to PM and PM to
AM.
I am formatting my start and stop time as h:mm AM/PM and my result of the
above formula as [m].