Issue: You are trying to register for courses for a semester and the courses are listed to select from but at the side view you are not able to check the add or drop check boxes nor are they visible for you to modify.
Possible Reasons: You have not been cleared by your advisor to add/drop courses.
Possible Reasons: It has not been cleared to do so by the school's department or not within the Add/Drop period
Possible Reasons: You have not checked "acknowledge the registration agreement"
Please consult with you advisor if any of the above apply.