Google Hosted Mail Shared Contacts

I’ve set up another domain’s email system using Google’s Hosting for Domains, and got really excited when there was a checkbox labelled: Share User’s Contacts, thinking that I could set up an address book for one user, and share it among all of them. This was just what I needed for the organisation, which I help administer. However, it only adds the users to each other’s address books, not every user they add to their contacts…