How to add new router to project

I developing exam feature
I want create page detail exams. But when i add

{
   path: 'exams/:qid',
   page: 'pages/Exams/Detail',
}

and create pages/Exams/Detail/index.tsx

const Index = () => {
  return <div>Exam page</div>;
};

export default Index;

When i go to to http://localhost:3000/exams/D1qo1 then screen show loading

How to add new page? Please help me!