title: Why my super simple ASP.NET Web API (mvc4)+Entity Framework 5 doesn't work?
body: <p>I spent days to know the problems of my work, but no luck.</p>
  
  <ol>
  <li>I created new MVC4 Web API project.</li>
  <li>Add EF5 with my database (Project>Add>ADO.NET Entity Data Model>Create from database which is in Azure SQL).</li>
  <li>Add two tables to edmx as below. And two *.tt files generate entities and model classes successfully.</li>
  </ol>
  
  <p><img src="https://i.stack.imgur.com/UAzak.png" alt="enter image description here"></p>
  
  <p><strong>I can see the breakpoint(result) gives query result normally.</strong>
  But json gives abnormal stream without error message. (ie, <code>http://localhost:41813/api/sheet/157</code> returns "157" which cannot download. in general, "157.json" is downloaded)</p>
  
  <p><img src="https://i.stack.imgur.com/4UJ7r.png" alt="enter image description here"></p>
  
  <p>I copied properties in results to my handmade POCO-style class and it works.</p>
  
  <p>What is my problem? I cannot use generated model classes to send data through Json.
  I hardly find out problem because no error message and no debug step available after the result breakpoint.</p>