Difficulty Creating Dynamic Distribution Group Filter in EMS

Hello,

We've just moved our exchange server's to exchange 2010 from 2003, and I'm looking at how to create query-based distribution lists in the newer version. 

Essentially what I want to do is create dynamic distribution lists based on the MailBox database the user is in. So far I tried this in the EMS:

$Database = (Get-MailboxDatabase "Staff-Mail Store")

New-DynamicDistributionGroup AllStaff -RecipientFilter {Database -eq $Database} -RecipientContainer "OU=Users List,DC=MyDomain,DC=com" -OrganizationalUnit "OU=Exchange,OU=Distribution Groups,DC=MyDomain,DC=com" 

But when I go and look at the filter preview inside the EMC I'm not seeing any of the users I want, or any user for that matter, just some other groups.

Can anyone here point me in the right direction? I'm assuming at this point I may be going about this the wrong way. Also, does anyone know if it's possible to include more than one database parameter in the filter? Exchange 2003 seemed to be limited to one.

Any help is appreciated. Thanks.