How to restrict combining two leave types?

Summary

How to restrict combining two leave types?

Content

Hi All,

How to block leave combining? We need to block when an employee combines “Annual leaves” with “casual Leaves”. We have tried to write a validation formula. Still, we were not able to succeed. Is there is any other way to achieve this goal? Our Requirement is, Employee cannot combine Casual leave and Annual leave. For example

• The annual leave end date cannot be the date that next to the Casual leave (Schedule or pending approval).
• Annual Leave Start data cannot be the date that next to the Casual leave (Schedule or pending