Exchange items that were restored using FastBack for Exchange cannot be found in the mailbox. The restore might be successful but the item is not displayed or cannot be seen.
The restored Exchange item is not displayed in the mailbox or the restore may fail to report the item already exists, although it cannot be seen
The problem might happen if the mailbox is a disconnected mailbox.
Resolving the problem
One of the common reasons this problem can occur is when the mailbox that you are trying to recover has been disconnected. For Exchange 2007 and Exchange 2010 Server, the Exchange powershell command "Get-DisconnectedMailbox" can be used to obtain a list of the disconnected mailboxes.
To resolve this problem where the mail item(s) are not being seen, the disconnected mailbox should be removed and then attempt the recovery steps again.
Purging a disconnected mailbox can be performed with the "Remove-DisconnectedMailbox" powershell command for the Exchange 2007 and Exchange 2010 Server.
Note: Microsoft support should be contacted for additional information or assistance with these Exchange powershell commands