Before scheduling the shift, you must set all shift timetables possibly used. Only in this way can various parameters set be valid.
Choose Attendance >Timetable to access the Timetable interface:

The system will set a default shift with the name of Flexible Timetable.
Flexible Timetable: Work delay is not counted as overtime, and late arrival, early leaving or absence is not calculated. The attendance for a flexible time period is calculated by the even number of card-punching times. The line numbers of its report are generated automatically. If four records exist, the daily report on that day has two lines. If six records exist, the daily report has three lines. Besides, the attendance time in a time period is check-out time minus check-in time.