When running the Server Storage report, the server(s) return a storage size of 0 MB. MessageStats may log following error in it application logs
'An error occurred in finding the file, \\<servername>\<drive>$\<storepath>\<storename>.edb. The file may not exist or the current user does not have rights to the file' and/or
'An error occurred in finding the file, \\<servername>\<drive>$\<storepath>\<storename>.stm. The file may not exist or the current user does not have rights to the file.
Please ensure that access is granted to the Exchange Server's hidden drive where the .EDB and .STM files are located. Also ensure that the Admin shares are present and accessible.
