Usually a person gets an error saying that they don't have the permission to do something when they do not have the right role or a group assigned to them. Check their account in Security Management and see if they have the correct Roles and Groups assigned to them for the department that they were trying to edit something in.
Campus Suite Tip - If one person has the rights to a department and another one needs to have the same rights. We recommend opening one account in a window and the second in another window. That way it will be easier to match settings between the two accounts.