"Accept Proposal" button is dimmed/unable to be clikced on a calendar entry
 

Hi,

I am running Outlook 2003. Upon receiving a "New Time Proposed" email,
I intended to accept the proposed time, but I am unable to click the
"Accept Proposal" button because it is dimmed/unable to be clicked.

Help is most certainly appreciated to enable me to do so.
Additionally, some new calendar entries are not showing in my calendar.

Thanks much,

Paul