Under Tools->Options-> MS Exchange, have you enabled the Restore Individual mailboxes from the Information Store, and if necessary, disabled the Legacy support? The wording is not correct, but you should get the idea.
Also, if you look at your backup folder, you should see a sub-folder or two, with a number of .edb, log and other suffix files. If not, then you need to enable individual restores as above from your main Console window. Make sure your backup job(s) also have/has that box checked.