Problem staff on the diary screen

I am having a problem displaying the correct staff present in the main diary page. It would list staff members who are not working that day, and not list members who are present. 

This is despite having set the working times for all staff. It is set to “View appointments by staff” and “Auto select working staff for date”. Please advise if I need a different setting?
 
Kind regards,
Mike Shiew
Manager, Camden & St Pancras Physiotherapy Clinics