Outlook 2007: adding an archive file

[Dan2]

I want to add an Archive file to the Navigation/ Mail Folders pane.

• I click File | Data File Management |
• The Account Settings box pops up
• I click Data Files | Add
• In New Outlook Data File box I select Office Outlook Personal Folders File (.pst) and click OK
• In Create or Open Outlook Data File, I select the desired file and click OK
• The box Microsoft Office Outlook pops up with the message "The requested operation failed". No reason is given.

Thank you for your help.
Dan