AJAX.NET triggers don't fire

[Troy Donavan]

The idea here is to get the user's country, state and city and when the
country is selected the selections for state would be updated and similarly
for state, when a state is selected the selections for city would be updated.
Unfortunately, none of the triggers are firing. Any idea why?

Here is the code in a page with three DropDownList controls.

<%@ Page Language="VB" MasterPageFile="~/TasiAsp.master"
AutoEventWireup="false" CodeFile="Default.aspx.vb" Inherits="_Default"
title="Untitled Page" %>
<asp:Content ID="ContentLogIn" ContentPlaceHolderID="ContentPlaceHolder1"
Runat="Server">

<asp:UpdatePanel ID="UPCountry" runat="server">
<ContentTemplate>


<aspropDownList ID="DDCountry" runat="server" style="z-index: 100;
left: 500px; position: absolute; top: 100px; width: 200">
</aspropDownList>

</ContentTemplate>
</asp:UpdatePanel>




<asp:UpdatePanel ID="UPState" runat="server">
<ContentTemplate>
<aspropDownList style="Z-INDEX: 100; LEFT: 500px; WIDTH: 200px; POSITION:
absolute; TOP: 130px" id="DDState" runat="server" __designer:wfdid="w4">
</aspropDownList>
</ContentTemplate>
<triggers>
<asp:AsyncPostBackTrigger ControlID="DDCountry"
EventName="TextChanged"></asp:AsyncPostBackTrigger>
</triggers>
</asp:UpdatePanel>





<asp:UpdatePanel ID="UPLocality" runat="server">
<ContentTemplate>
<aspropDownList style="Z-INDEX: 100; LEFT: 500px; WIDTH: 200px; POSITION:
absolute; TOP: 160px" id="DDLocality" runat="server" __designer:wfdid="w5">
</aspropDownList>
</ContentTemplate>
<triggers>
<asp:AsyncPostBackTrigger ControlID="DDState"
EventName="TextChanged"></asp:AsyncPostBackTrigger>
<asp:AsyncPostBackTrigger ControlID="DDCountry"
EventName="TextChanged"></asp:AsyncPostBackTrigger>
</triggers>
</asp:UpdatePanel>


</asp:Content>