I'm working through the Client side cascade example in the WebDropDown section.  I'm trying to implement this into my application.  However, the WebDropDownDataCommand is not recognized.  I've included all the same references as the example is using.  I'm using the 3.5 framework.  What am I missing?

protected void Page_Load(object sender, EventArgs e)

{

if (!IsPostBack)

{

WebDropDown1.Items.Clear();

WebDropDownDataCommand wddc = new WebDropDownDataCommand();

IList<WebDropDownItem> list = wddc.GetData(); WebDropDown1.DataSource = list; WebDropDown1.CurrentValue = "";

}

}