outllook 2k calendar sharing

Outlook in Office 2000 professional when sharing calendars, ‘A’ sends invitation for share with ‘B’. ‘B’ recieves notification. Upon opening messages appears: “Email address does not match the default email address. You should not accept/decline invitation if you are not the intended recipeient.” ‘B’ is then able to open the invitation. However, the calendar is not updated on B’s machine. I have done everything in the Microsoft KB and still no luck. Using MS Mail on a Win2k Ad. Server. thnx