I've written the formula below, but I'm getting a result of zero. I'm trying
to sum cells C5:C750 where cells D5:D750 are equal to either a zero or an
#N/A value.

By just specifying the zero or just specifying the #N/A, I get the correct
result, but I need to combine the two.

=SUMIF('Business Both Years'!D5:D750,"0"&"#N/A",'Business Both Years'!C5:C750)

Any ideas?