Element 'DropDownListX' is not a known element.
<p>I have used the class in my project. But I have warning  <code>Element 'DropDownListX' is not a known element</code>  in source view page <code>default.aspx</code>. In design view shows the control.</p>

<p>even in <code>default.aspx.cs</code> is known <code>dropdownlistx</code></p>
