A Work Schedule Profile and Leave Entitlement Profile need to already be created and set accordingly for the employee. In this case, the system will give the employee the appropriate leave entitlement accordingly.
If a step was skipped (i.e. creation of profile or setting up of employee), or if you inserted the leave entitlement later on, the system will not assign leave entitlement by itself. In this case, you will need to either input leave entitlement manually, OR re-calculate an employee's leave entitlement by using the button as shown below (Leave Entitlement tab).
This will refresh and recalculate the employee's leave entitlement.