Use this command
$Database= (Get-MailboxDatabase "Staff-Mail Store"). distinguishedName
And then type $Database in the shell and let me know if its retuning the Distiished name of the Staff –Mail Store
Jasjit Singh Dhindsa | ITIL v3 | IASA Foundation Certified | MCITP:Exchange 2010 | Exchange 2007 | MCTS:OCS 2007 | Exchange 2010 | Exchange 2007 | MCSA:Messaging | Security | MCSE:Messaging | Security