Mandatory people picker field based on two conditions: condition A and condition B

I am building a form for making appointments with these fields:

• Appt Category (Choice): Make appointment or block appointments
• Supervisor (people picker)
• Supervisor Not Listed (checkbox yes/no - default is no)
• Supervisor (Manual Entry) - text field

I already have a rule where ‘Supervisor (Manual Entry)’ is a required field when ‘Supervisor Not Listed’ is equal to ‘Yes’…

But need a validation rule to make the ‘Supervisor’ (people picker) field MANDATORY on these two conditions. I tried this rule, but it does not work:  

• ‘Appt Category’ = “Make appointment” AND
• ‘Supervisor Not Listed’ is equal to ‘No’

So that when ‘Appt Category’ = “block appointments”, the supervisor fields are not mandatory.

Thank You.