title: The type of namespace name 'Control' could not be found (are you missing a using directive or assembly reference?)
body: <p>Trying to set up an extension method in .Net 3.0 using generics and I get an error message, details above on the line:</p>
  
  <pre><code>foreach(Control childControl in parent.Controls)
  </code></pre>
  
  <p>Am I missing a using directive or assembly reference?</p>
  
  <p>Thanks</p>
  
  <p>What I am trying to do is set this up (below) as an extender function:</p>
  
  <pre><code>using System;
  using System.Collections.Generic;
  using System.Web;
  using System.Web.UI;
  
  namespace System.Runtime.CompilerServices
  {
      public static class ControlHelper
      {
      public static T FindControl&lt;T&gt;(this Control parent, string controlName) where T : Control
      {
          T found = parent.FindControl(controlName) as T;
          if (found != null)
              return found;
          foreach (Control childControl in parent.Controls)
          {
              found = childControl.FindControl(controlName) as T;
              if (found != null)
                  break;
          }
          return found;
      }
  }
  }
  </code></pre>
  
  <p>I am missing a reference to the system.core.dll... its driving me nuts!</p>