Question : Can't change link source from one workbook to its apparently identical twin.

Please take a look at these 4 workbooks. Dummy Template.xls is linked to DEC-09.xls.
NOV-09.xls and SEPT-09.xls are identical in structure to DEC-09.xls. I can easily change  the link from DEC-09.xls to NOV -09.xls. However when I try to change the source to SEPT-09.xls, I get a "formula in this worksheet contains one or more invalid references."

There don't appear to be any invalid references in SEPT-09.xls. Control-G for formulas with errors returns nothing. So why am I getting that error?  Is the SEPT-09 workbook corrupted in some way? If  not, how do I fix it?

Thanks,

John

Answer : Can't change link source from one workbook to its apparently identical twin.

The SEPT-09.xls workbook does not have a sheet called Sheet1 in it... :)