Recovering deleted items from other user's folder

Hello.
There are some users whose mailboxes contain deleted items.  I need to recover these deleted items through Outlook.  To that end, I have added their Exchange accounts to the list of accounts that are opened when Outlook starts.
I have given myself the "Full Mailbox Access" permission to each of the user's mailboxes in Active Directory.  However, when I click on the Deleted Items folder for one of the users, the "Recover Deleted Items" button is grayed out.  It is available on my personal accounts, but not on the other users'.
Please help me with enabling this option so I can recover these deleted items remotely.

Thanks.