I am using a SUMIF statement to return values when locating a specific text
string from external files. The SUMIF statement works perfectly if I have
the external files open. However if I don't have the external files open,
all my SUMIF formulas change to #VALUE! Is this a limitation because I'm
searching for text? Is there a way around this error without having to open
all 24 external file links everytime I want to view this report?

Here's what my formula:

=SUMIF('G:\[File.xls]Output 1'!$A:$A,"312 Non-Exempt Labor -
Fixed",'G:\[File.xls]Output 1)'!$B:$B)