can’t get generated controls through AJAX response

Question

I use ASP.NET C# with AJAX Professional (http://www.ajaxpro.info)

1) I have a div container with Panel control, Panel control should hold DropDownList that will be generated in codebehind function:

<div id="divDDL" runat="server">
    <asp:Panel ID="Panel1" runat="server">
    </asp:Panel>
</div>

2) I have a JS script function "getDDL" that sends data to codebehind

function and then it receives response with generated Panel and

DropDownList controls:

function getDDL(lng)
{
    MyCodebahindClass.GetDDL(0, lng, callbackDDL);
    //callbackDDL is a response function
}

function callbackDDL(response)
{
    //here the response with the generated DropDownList and Panel control comes to the div element
    document.getElementById('<%=divDDL.ClientID %>').innerHTML = response.value;
}

3) Codebehind function "GetDDL" must return generated DropDownList inside the Panel control:

[Ajax.AjaxMethod]
public Panel GetDDL(int itemId, int lng)
{
     PanelID = Panel1.ID;
     DropDownList rubricDDL = new DropDownList();
     rubricDDL.ID = "Fashionable_Catheter";
     rubricDDL.DataTextField = "title";
     rubricDDL.DataValueField = "id";
     rubricDDL.DataSource = %LINQ STUFF%;
     rubricDDL.DataBind();

     panelID.Controls.Add(rubricDDL);
     return panelID;
}

4) When I try to get the generated Panel and DropDownList through the JS response I receive only the text "System.Web.UI.Design.Panel" or something like that, tried to generate only DropDownList - similar text shows up "System.Web.UI.Design.DropDownList".

But when I call a codebehind function to get these two controls I see them without any problems. Why I can't get them through JS? I do everything fine, debugged million times and didn't see any problems, I can't figure out what's wrong with JavaScript? Any help much appreciated.