Excel has difficulty executing some formulas with links to closed
workbooks.  I can't say I am surprised since it must have to do a lot
of work to determine the contents of the cells without fully opening
the workbook concerned.

Ways in which you might be able to help it:
- open the file<g> (you could do that by macro on opening the
destination file, and you could open it read-only to reduce the
interaction with other users)
- include the formula result in a cell in the source workbook and just
reference that single cell in the linked formula
- use a named range in the source workbook rather than an address like
$E$7:$G$21 (I'm not sure this helps, but it might; it certainly makes
maintenance simpler because you can insert rows and columns in the
source workbook without having to remember to have the destination book
open at the time).

Bill Manville
MVP - Microsoft Excel, Oxford, England
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