Filter appointments shown in Calendar


Is there a way, to filter the Appointments which are shown in the Calendar?

E.g. when an Appointment is cancelled, this is recorded in the Table. Based on this "cancelled" can i hide/filter that this element is not shown anymore in the calendar (an not sync'd)?

When putting an "if" in the formula for the "Show As" it gives and "undefined" when it is empty.

Any help appreciated.