title: The controller for path '/' was not found... error in Html.Action
body: <p>My application (ASP.NET MVC 4) was working until a few hours ago and just recently I got this error:</p>
  
  <blockquote>
    <p>The controller for path '/' was not found or does not implement IController</p>
  </blockquote>
  
  <p>I test parts of application and find that it will be happend when I call a <code>Html.Action</code> or <code>Html.RenderAction</code> helper. I should tell you I googled and SOed the error and find some articles but none of them resolved the problem. It seems every thing is OK. My routing system and calling the helpers and... every thing seems is OK. Is there any bit point about using <code>Action</code> and <code>RenderAction</code>? </p>
  
  <p>OH, I should to tell you, it happened just after I copy/paste some controller and views from another project to current project. But I check namespaces and files exists and every thing. Any suggestion please? I am currently hanged.</p>