Controller unit test issue with constructing URL

One of my API Controller method routes is "api/Students/GetList". It accepts two parameters: 'studentKey' and 'isSenior'

If I call this method from my unit test as follows then it works fine:

.....Get("api/Students/GetList/Super/false", Server)

But if I call as following it does not go to the method's break point and complains about "method not found":

.....Get("api/Students/GetList/?studentKey=Super&isSenior=false", Server);

Why? What's wrong with my second URL?