Exchange Single Information Store Backup

Hello
I’m trying to setup a Exchange 2003 Single Information Store Backup.

I’d like to backup only the mailboxes located in one Exchange Information Store, using Data Protector V.06, but I have the following problem.

Configuring the Exchange System Manager, if I assign to the Exchange Admin User the administration rights to manage on the Exchange Server, by DP I can expand the Mailbox tree and I can view all mailboxes (on the all Infromation Stores), but I want to view only the mailboxes located in a specified Store (or I want the possibility of select all the mailboxes of a specified Store)

Instead, if I assign to the Exchange Admin User the administration rights to manage only on the Information Store I want, using DP I cannot expand the Mailboxes object (An error has occurred while retrieving rows from table)

Can someone help me?

Thanks in advance.