TagMapping - doesn't work for Telerik

[wnl]

Hi,
I want to add a tag mapping in web.config. In my web app it works for standard controls (label) but not for RadMenu. Version of my Telerik: 2010.1.519.35. Why?

<tagMapping>
        <clear />
        <add tagType="System.Web.UI.WebControls.Label" mappedTagType="NoVSLabel"/>
        <add tagType="Telerik.Web.UI.RadMenu" mappedTagType="NoVSRadMenu"/>
</tagMapping>

I prepared classes, one of them (for Telerik):

public class NoVSRadMenu : Telerik.Web.UI.RadMenu

{

    public NoVSRadMenu()

    {

        EnableViewState = false;

    }

}