Getting a #ref! when using indirect with sumproduct

I am currently using the following function to sum a column in an external spreadsheet:

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D13 value is the full name of the external file (ie. C:\Documents and Settings\g1gq\Desktop\Weekly Resource Report\Source Data\BRT Weekly Resource Report_3-22-11.xls)

Any thoughts?

See the answer in your other post.

http://www.excelforum.com/excel-prog...ncatenate.html