ajax auto compelete extender not working.

i have tried to put a ajax autocomplete extender integrated with a textbox in my web page. But it doesn't seem working. cheked the execution flow insrting breakpoint.Figured out that page service can't be called from the ajax autocomplete extender.
     here i m putting the both codebehind file(.cs) and aspx page.
 
<asp:ToolkitScriptManager ID="ToolkitScriptManager1" runat="server" EnablePageMethods="True">

</asp:ToolkitScriptManager>


<asp:TextBox ID="searchbox" runat="server" style="z-index: 1; left: 404px; top: 26px; position: absolute; height: 40px; width: 281px"
AutoCompleteType="None" ClientIDMode="Static"></asp:TextBox>

<asp:AutoCompleteExtender ID="searchbox_AutoCompleteExtender" runat="server"
DelimiterCharacters="" Enabled="True" MinimumPrefixLength="1"
ServiceMethod="getlist" TargetControlID="searchbox"
CompletionInterval="1000"> ...