title: Extension method not found (not an assembly reference issue)
body: <p>I have the following extension method:</p>
  
  <pre><code>public static EntitySet&lt;T&gt; ToEntitySetFromInterface&lt;T, U&gt;(this IList&lt;U&gt; source)
      where T : class, U
  {
      var es = new EntitySet&lt;T&gt;();
      IEnumerator&lt;U&gt; ie = source.GetEnumerator();
      while (ie.MoveNext())
      {
          es.Add((T)ie.Current);
      }
      return es;
  }
  </code></pre>
  
  <p>and Im attempting to use it as follows:</p>
  
  <pre><code>   List&lt;IItemMovement&gt; p = new List&lt;IItemMovement&gt;();
      EntitySet&lt;ItemMovement&gt; ims = p.ToEntitySetFromInterface&lt;ItemMovement, IItemMovement&gt;();
  </code></pre>
  
  <p>where ItemMovement implements IItemMovement. The compiler complains:</p>
  
  <blockquote>
    <p>'System.Collections.Generic.List' does not contain a
    definition for 'ToEntitySetFromInterface' and no extension method
    'ToEntitySetFromInterface' accepting a first argument of type
    'System.Collections.Generic.List' could be found (are
    you missing a using directive or an assembly reference?)</p>
  </blockquote>
  
  <p>No I'm not missing a reference. If I just type the name of the static class containing the method it pops up and so does the extension method. Thnx</p>