Sharing a calendar in Outlook 2003

When trying to share a calendar in Outlook 2003. I clicked on “Share My Calendar” and these three tabs are missing…”Administration”, “Permissions”, and “Forms”. I have checked to make sure that “Exchange Extensions commands” and Exchage Extensions property pages” are checked. I also removed them, restarted Outlook and added them back and restarted Outlook again and this has not worked. Any help with this would be appreciated.

Thank You.