How do I add a third association

Question

Adding a third associative does not work -- it there a workaround to have three association classes?

Here is an example:

@startuml test
class Student {
  Name
}
Student  *--  Course
(Student, Course) . Enrollment

Student  *--  Course
(Student, Course) . Second

Student  *--  Course
(Student, Course) . Third  <-- remove this line and there is no error

class Enrollment {
  drop()
  cancel()
}
@enduml