ASP.NET updatepanel not refreshing the dropdownlist controls - ajax

Question

I have recently added a updatepanel in my aspx page. My controls are inside a HTML table, labels, dropdownlist etc. And i want the dropdown lists to refresh only.. but no hope at all.. any help..
The sample code is below
<asp:UpdatePanel ID="UpdatePanel1" runat="server" RenderMode="Inline">
<ContentTemplate>
<table id="Table5" height="50" cellspacing="3" cellpadding="3" width="200" border="1">
<tr>
<td width="110" height="21">
<p align="left">
<asp:Label ID="lblDomain" runat="server" CssClass="reportOption" Width="51px">Domain</asp:Label></p>
</td>
<td width="110" height="21">
<p align="left">
<asp:Label ID="lblSystem" runat="server" CssClass="reportOption" Width="51px">System</asp:Label></p>
</td>
<td style="width: 86px" nowrap width="86" height="21">
<p align="left">
<asp:Label ID="lblVendor" runat="server" CssClass="reportOption" Width="88px">Select Vendor</asp:Label></p>
</td>
<td>
<asp:Label ID="lblRegion" runat="server" CssClass="reportOption" Width="77px">Select Region</asp:Label>
</td>
<td>
<asp:Label ID="lblNode" runat="server" CssClass="reportOption" Width="80px">Select Node</asp:Label>
</td>
<td>
<asp:Label ID="lblRouteType" runat="server" CssClass="reportOption" Width="91px"
Visible="False">Select Route Type</asp:Label>
</td>
<td>
<asp:Label ID="lblRoute" runat="server" CssClass="reportOption" Width="80px">Select Route</asp:Label>
</td>
<td>
<asp:Label ID="lblUtil" runat="server" CssClass="reportOption" Width="80px">Enter Utilization > than</asp:Label>
</td>
</tr>
<tr>
<td width="51">
<asp:DropDownList ID="ddlDomain" runat="server" CssClass="reportOption" Width="89px"
AutoPostBack="True">
<asp:ListItem>National</asp:ListItem>
<asp:ListItem>International</asp:ListItem>
<asp:ListItem>[All]</asp:ListItem>
</asp:DropDownList>
</td>
<td width="51">
<asp:DropDownList ID="ddlSystem" runat="server" CssClass="reportOption" Width="55px"
AutoPostBack="True">
<asp:ListItem>NNN</asp:ListItem>
<asp:ListItem>III</asp:ListItem>
<asp:ListItem>TTT</asp:ListItem>
</asp:DropDownList>
</td>
<td width="50">
<asp:DropDownList ID="ddlVendor" runat="server" CssClass="reportOption" Width="91px"
AutoPostBack="True">
</asp:DropDownList>
</td>
<td>
<asp:DropDownList ID="ddlRegion" runat="server" CssClass="reportOption" Width="80px"
AutoPostBack="True">
</asp:DropDownList>
</td>
<td>
<asp:DropDownList ID="ddlNode" runat="server" CssClass="reportOption" Width="80px"
AutoPostBack="True">
</asp:DropDownList>
</td>
<td>
<asp:DropDownList ID="ddlRouteType" runat="server" CssClass="reportOption" Width="80px"
Visible="False">
</asp:DropDownList>
</td>
<td>
<asp:DropDownList ID="ddlRoute" runat="server" CssClass="reportOption" Width="80px">
</asp:DropDownList>
</td>
<td>
<asp:TextBox ID="tbUtil" runat="server" CssClass="reportOption" Height="20px" Width="51px">0.0</asp:TextBox>
</td>
</tr>
</table>
</ContentTemplate>
</asp:UpdatePanel>
And yes the script manager is there too..
<asp:ScriptManager ID="AjaxScriptManagerforDDL" runat="server">
</asp:ScriptManager>

Answer 1

This code is fine, you have placed your dropdowns in update panel, and all your dropdowns are Autopostback=true.
Clearly when you select any value from dropdownlist, page should not get refreshed. Thats what is happening with this code.
I created a aspx page, added a script manager, and then added your code, its working fine.