If the Exchange Stores are not visable in Backup Manager this is normally due to circular logging being enabled.

 

There can be a problem selecting the Exchange databases in the IASO. When clicking on Exchange, no file-tree is expanded.

Solution of the problem is to start regedit and find the following key:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\MSExchangeIS\ParametersSystem\Disable Exchange Writer
The value for that key should be set to '0'. After that, restart the Microsoft Exchange Information Store service and restart the Backup Manager.

The databases should now be selectable.

If the key 'Disable Exchange Writer' is not there then create it with a value of 0