title: Custom html helpers in MVC 4
body: <p>I created the helper class</p>
  
  <pre><code>namespace SEM.API.Helpers
  {
      public static class Navigation
      {
          public static string BuildSomething(this HtmlHelper helper)
          {
              return "empty";
          }
      }
  }
  </code></pre>
  
  <p>And added the namespace to webconfig <code>&lt;add namespace="SEM.API.Helpers" /&gt;</code>
  but I still getting an error:</p>
  
  <blockquote>
    <p>CS1061: "System.Web.Mvc.HtmlHelper"</p>
  </blockquote>
  
  <p>It isn't solved after a lot of rebuilds</p>