Why is the chart not being completed?

Question

C++ / C#

The problem is that the class constructor does not completely make connections, why?
Logically, he must also refer to IDetail from 2 classes, but does not do this, but simply signs it from above. How to fix?

Answer 1

Classes do not refer to or inherit an interface, they implement it, so you have an implementation listed next to each class.
If you want communication, then instead of an interface, create an abstract class.