Description:
The following error shows up when you try to save a newly created Time Off type: Time Off Types with "Booking Required" checked must also have "Display on Calendar" checked. (Refer the image below)

                             

Cause:
This issue is usually noted for Time Off types which has Booking Required option enabled, however it does not have Display on Calendar enabled. The error informs the user that you have to enable the Display on Calendar setting.

Resolution:
Ensure that Display on Calendar is enabled for Time Off types that have Booking Required enabled.