Unable to cast object of type 'ASP.masterpage_mpname_master' to type 'ITest'
<p>I am developing a web application. I have created an interface ITest</p>

<pre><code>public interface ITest
{
    void Add();
}
</code></pre>

<p>&amp; a usercontrol which implements ITest</p>

<pre><code> public partial class WebUserControl1 : System.Web.UI.UserControl, ITest
    {
        public void Add()
        {
            throw new NotImplementedException();
        }
    }
</code></pre>

<p>On my webpage i have placed usercontrol. but, when i typecast the usercontrol to type IType it throws an Exception(System.InvalidCastException)</p>

<pre><code>  protected void Page_Load(object sender, EventArgs e)
    {
        if (!IsPostBack)
        {
  //          WebUserControl11.Add();
            foreach (var uCnt in this.Page.FindControlsOfType&lt;UserControl&gt;())
            {
                if (uCnt.Visible)
                {
                    ((ITest)uCnt).Add(); //Error : Casting Exception
                }
                else
                {
                }
            }
        }
    }
</code></pre>

<p><strong>I can call Add method directly</strong> but, I want to call it using ITest Interface</p>
