autocomplete extender not working inside modal popup extender

See more:

C#

ASP.NET

I am opening a popup in which i have a textbox.i want to use ajax autocomplete extebder for this textbox.but its not able to call the webservice method for autocompletion.cant understand weather its a problem of postback or updatepanel.where i should use the update panel.My page containing popup div is already inside "updatepanel1" .code snap is given below..

<asp:UpdatePanel ID="UpdatePanel2" runat="server" UpdateMode="Conditional" ChildrenAsTriggers="false" >
                                            <contenttemplate>
<asp:TextBox ID="txtEditMPName" runat="server" Width="408px" AutoPostBack="true" BackColor="#CCFFFF" OnTextChanged="txtEditMPName_TextChanged">
<cc1:AutoCompleteExtender ID="ace2"  runat="server" BehaviorID="autoSuggest" DelimiterCharacters="" Enabled="true" MinimumPrefixLength="1" ServiceMethod="GetParty" CompletionInterval="10" EnableCaching="true" CompletionSetCount="1"  önClientShown="ShowOptions" TargetControlID="txtEditMPName" FirstRowSelected="True" CompletionListCssClass="AutoCompleteCompletionList" CompletionListHighlightedItemCssClass="AutoCompleteCompletionListHighlightedItem" CompletionListItemCssClass="AutoCompleteCompletionListItem">

</contenttemplate>
 <triggers>
<asp:AsyncPostBackTrigger ControlID="txtEditMPName" EventName="TextChanged" />
</triggers>