Ajax Auto Complete Extender Not Working Inside Grid

Please Note That

I have and ProfileEducation.ascx and Profile.aspx ...ok

I used ascx file for HTML and other things and drag into aspx to use as tool, or control

I have GridView in ProfileEducation.ascx and it has Following

<asp:UpdatePanel ID="UpdatePanel5" runat="server"><contenttemplate><asp:TextBox ID="txtInstitute" runat="server" Height="25px" Width="265px"></asp:TextBox><Syed:AutoCompleteExtender ID="txtInstitute_AutoComplete"  runat="server"
            Enabled="True" ServiceMethod="GetList_Autocomplete" MinimumPrefixLength="1" EnableCaching="false"
            TargetControlID="txtInstitute"  
                         CompletionInterval="100" CompletionSetCount="1" 
                                    ServicePath="" 
                                    UseContextKey="True"> </Syed:AutoCompleteExtender></contenttemplate></asp:UpdatePanel>  

and When I used Following as c# code for show list of Institute then strange thing happen ....

My c# code which Intialy I used in ProfileEducation.ascx.cs are below

        [System.Web.Script.Services.ScriptMethod()]
        [System.Web.Services.WebMethod]
        public static string[] GetList_Autocomplete(string prefixText, int count)
        {
            string[] arr2 = { "one", "two", "three" };

            return arr2;

        }

but its was not working even the code was not red by Visual studio and its not stop onBrakpoint , its mean its never executed,  but when I copy the above code on

Profile.aspx.cs then its pause or stops on Brakpoint which I used tocheck GetList_Autocomplete is working(executing) are not....
now the VS reads every line but do not return array list

but when I Move HTML Outside the grid along with updatepanel

then its work but showing list horizontally istead of vertically

like : onetwothree (Horizontally)

why...?

first help me out

1) why HTML of ProfileEducation.ascx (autocompleteextender ServiceMethod ) readProfile.aspx.cs ....? instead of ProfileEducation.ascx.cs
2) If read then why showing horizontally instead of vertically?

3) if show horizontally then why its stop working when I put Iside the gridview...?