Hello Chad,

Yes, indeed, I was able to reproduce the very same javascript error while trying to programmatically add a UltraWebListbar instance to a placeholder. After scratching my head and trying different things for a good 15 minutes, it turned out that UltraWebLisbar expects you to explicitly set and ID in order to register its client-side instance using javascript. Now that I think about it, this actually makes sense, however I believe we should add an exception that explicitly asks for an ID, since the javascript error is indeed not descriptive at all.

Here is my sample setup:

   <asp:PlaceHolder ID="PlaceHolder1" runat="server"></asp:PlaceHolder>
   
    protected void Page_Load(object sender, EventArgs e)
    {
        UltraWebListbar ultraWebListBar1 = new UltraWebListbar();

        ultraWebListBar1.ID = "ultraWebListBar1";
        ultraWebListBar1.Groups.Add(new Group("First Group"));
        ultraWebListBar1.Groups.Add(new Group("Second Group"));
        ultraWebListBar1.Groups.Add(new Group("Third Group"));

        PlaceHolder1.Controls.Add(ultraWebListBar1);    
    }

Hope this helps.