Since you can't import to a folder in the Public Folders hierarchy, it's unclear what you're trying to do. Please provide more complete details, along with the exact text of the error message.
--
Sue Mosher, Outlook MVP
Author of Configuring Microsoft Outlook 2003
and Microsoft Outlook Programming - Jumpstart for
Administrators, Power Users, and Developers
First, forget export/import. Open your private Contacts folder. Select all
the entries with CTRL-A. Click Edit>Copy to Folder. Specify the public
folder as the destination. Click OK.