Outlook 2K Contacts Problem

I have imported a new employees Contacts in the form of a .pst. The new Contacts list shows up in the current Outlook, but it will not let me go into properties and select it to be viewed as an address book. The “show as an address book” box is greyed out. I have never seen this before. Is there some setting elsewhere that would cause this to happen? Any ssuggestions would be greatly appreciated.