AutoComplete Texbox and Search ด้วย Vb.net 2010 + Sql Server 2005

<asp:hiddenfield id="hdnValue" onvaluechanged="hdnValue_ValueChanged" runat="server"/>

<asp:textbox runat="server" id="myTextBox" width="300" autocomplete="off" />
<ajaxtoolkit:AutoCompleteExtender runat="server" 
....
....
....
....
    onclientitemselected="OnSelected">
</ajaxtoolkit:autocompleteextender>

//update panel
//label ที่จะแสดงรหัส

function OnSelected(source, eventArgs) 
{  
    var hdnValueID = "<%= hdnValue.ClientID %>";

    document.getElementById(hdnValueID).value = eventArgs.get_value();
    __doPostBack(hdnValueID, "");
} 

protected void hdnValue_ValueChanged(object sender, EventArgs e)
{
    string selectedCustomer = ((HiddenField)sender).Value;

//query หารหัสแล้วเอาไป bind ลง label
}