Pivot Table - Error "Reference Is Not Valid"
 

I have created a pivot table which uses an external data source (oracle
database, through OLEDB)

The data is retreieved perfectly, the pivot table works fine, but whenever
data is refreshed (or if the query is edited), I receive the error message
"Reference is not valid"

I don't understand why this error is being shown, or how to get rid of it.
Anyone?

Excel 2007 on Windows XP, querying Oracle 9i db.

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Olly