How to perform validation and how to solve validation errors?

To learn how to request for approval, refer to below FAQ

What is the meaning?	How do I solve the problem?
1. You may add this course during the enrollment period.	Note that validation does not mean the seat is “reserved” for you. Remember to enroll the course(s) during enrollment period.
2. It is a warning message if a UG student tries to validate a PG course, or vice versa.	Seek “cross career” approval.
3. Student does not meet the enrollment requisite, which may include pre-/co-requisites or other conditions (e.g. only for a particular Major).	Seek “requisite waiver” approval. Note: This error message can also be triggered by course exclusion which cannot be waived according to university regulations
4. Permission from the instructor is required to enroll in this class.	Seek “instructor’s consent” approval.