cannot add dynamic distribution list to permissions list in Outlook

We have Exchange 2007 in an 2003 native forest/domain with Outlook 2003 running on the client side.  I want to configure Outlook permissions for a calendar a user has decided to share.  When I click the "add" button under the "Permissions" tab, I can see and select any of our dynamic distribution lists.  However, as soon as I click "apply" or "OK", it removes the dynamic distribution list from the list of configured permissions.  No errors are reported.  If I choose just a regular distribution list, it will accept it just fine.

My goal though is to have it so that any users can have access to this calendar (including new users, who will automatically get added to the dynamic distribution list due to me placing their user accounts in the corresponding OU).  Is there any way to do this without using public folders?  Or should Outlook be accepting the dynamic distribution list when I add it?