Distinguished Field Update

Ok.. I created a promoted field. I have code to update it as follows…

[code:1:facfe57dbe]strFileName = WorkInProgressFlatFile(FILE.ReceivedFileName);
WorkInProgressFileImportSqlRequest.FileImport.File = strFileName;[/code:1:facfe57dbe]

If the file contains only one record all works fine. When there is more than one record in the file (ie message) I get the following error.

[code:1:facfe57dbe]The result set for the XPath expression ‘/*[local-name()=’RecordInsertRequest’ and namespace-uri()=’http://XYZ.BizTalk.Schemas’]/*[local-name()=’FileImport’ and namespace-uri()=’http://XYZ.BizTalk.Schemas’]/@*[local-name()=’File’ and namespace-uri()=”]’ contains more than a single node. [/code:1:facfe57dbe]

How do I get it to update all promoted fields? Or just the one its on? I want to set the promoted field to the file name it came in on so I can store it in the database.

Thanks.