I am using the following function in Master.xls

=SUMIF(Source.xls!Colours,A1,Source.xls!Values)

As long as both workbooks are open, it calculates properly.

When I close both workbooks, reopen Master.xls & choose to update linked
formulas, the #VALUE error appears. I tried replacing named ranges with cell
references - same error.

As soon as I open Source.xls, the formula calculates properly.

Why is #VALUE appearing & how can I open only Master.xls & have the formuala
display the calculation?

I also have =SUM(Source.xls!Values) in Master.xls which does calculate
correctly when Source.xls is closed.

HELP!