Hi,
After seeing this, i've identified that you didn't have any primary key. Most often, ORM creates problem (its called problem of identity mapping, which we can discuss later). For now try to rewrite your query like:
var model = from x in dba. StaffAppointments
where x.StaffNo == 1
select x.Staffno, x.DateBooked, x.TimeFrom, x.TimeTo;
return View(model.ToList());
It should resolve problem...