ScriptManager not updating

晚上，我试图创建一个页面，从数据库中提取位置，并将其显示在网格视图中，然后这个网格视图指示出现在谷歌地图元素上的一些点。它在启动时运行良好，但当我使用文本框来细化gridview中的项目时，地图就会消失。我猜这是我的ScriptManager的问题，但我不确定确切的原因是什么。任何想法都将不胜感激。为代码墙道歉我只是有点不确定在这个阶段什么可能是相关的。

    <%@ Page Title="" Language="C#" MasterPageFile="~/Master.Master" AutoEventWireup="true" CodeBehind="Default.aspx.cs" Inherits="MapTest.Default" %>
<asp:Content ID="Content1" ContentPlaceHolderID="head" runat="server">
    <script type="text/javascript">
        function RefreshUpdatePanel() {
            __doPostBack('<%= txtSearch.ClientID %>', '');
        };
    </script>
    <script src="http://maps.googleapis.com/maps/api/js?key=AIzaSyA5U97yznzCvzDaUZjT3AydlQqyFBQVYc8&sensor=false">
    </script>
    <link href="App_Themes/Default/default.css" rel="stylesheet" type="text/css" />
</asp:Content>
<asp:Content ID="Content2" ContentPlaceHolderID="ContentPlaceHolder1" runat="server">
    <div class="Wrapper">
            <asp:ScriptManager ID="MasterScriptManger" runat="server"></asp:ScriptManager>
            <asp:UpdatePanel ID="upanSearch" runat="server" UpdateMode="Conditional" OnPreRender="upanSearch_PreRender">
                <ContentTemplate>
                    <div class="DataTable">
                        <span>Search</span>
                        <asp:TextBox ID="txtSearch" runat="server" onkeyup="RefreshUpdatePanel();"  onfocus="this.value = this.value;" OnTextChanged="txtSearch_TextChanged" AutoPostBack="True" AutoCompleteType="Disabled"></asp:TextBox>
                        <asp:GridView ID="grdLocations" runat="server" AutoGenerateColumns="False" DataSourceID="sqldsLocations">
                            <AlternatingRowStyle BackColor="#F6F6F6" />
                            <Columns>
                                <asp:BoundField DataField="Location Name" HeaderText="Location Name" SortExpression="Location Name" />
                                <asp:BoundField DataField="Latitude" HeaderText="Latitude" SortExpression="Latitude" />
                                <asp:BoundField DataField="Longitude" HeaderText="Longitude" SortExpression="Longitude" />
                            </Columns> 
                        </asp:GridView>
                        <asp:SqlDataSource ID="sqldsLocations" runat="server" ConnectionString="<%$ ConnectionStrings:MapTestGuestConn %>" SelectCommand="GetLocations(mySearch)" CancelSelectOnNullParameter="False" SelectCommandType="StoredProcedure">
                            <SelectParameters>
                                <asp:ControlParameter ControlID="txtSearch" Name="mySearch" PropertyName="Text" Type="String" />
                            </SelectParameters>
                        </asp:SqlDataSource> 
                    </div>
                    <div id="googleMap" style="width:500px;height:380px;"></div>
                    <script type="text/javascript">
                        initializeMap();
                    </script>
                </ContentTemplate>
                <Triggers>
                    <asp:AsyncPostBackTrigger ControlID="txtSearch" EventName="TextChanged"/>
                </Triggers>
            </asp:UpdatePanel>         
        </div>   
</asp:Content>
    using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Windows;
namespace MapTest
{
    public partial class Default : System.Web.UI.Page
    {
        protected void Page_PreInit(object sender, EventArgs e)
        {
            Page.Theme = "Default";
        }
        protected void upanSearch_PreRender(object sender, EventArgs e)
        {
            //MessageBox.Show(BuildMapScript());
            ScriptManager.RegisterClientScriptBlock(upanSearch, upanSearch.GetType(), "BuildMap", BuildMapScript(), false);
            //ScriptManager.RegisterStartupScript(upanSearch, upanSearch.GetType(), "BuildMap", BuildMapScript(), false);
        }
        protected void txtSearch_TextChanged(object sender, EventArgs e)
        {
            txtSearch.Focus();
        }
        protected string BuildMapScript()
        {
            grdLocations.DataBind();
            string markers = GetMarkers();
            string myScript = @"
                <script type='text/javascript'>
                function initializeMap() {
                var mapOptions = {
                center: new google.maps.LatLng(50.826108, -1.075011),
                zoom: 15,
                mapTypeId: google.maps.MapTypeId.ROADMAP
                };
                var myMap = new google.maps.Map(document.getElementById('googleMap'),
                mapOptions);"
                + markers +
                @"}
                </script>";
            return myScript;
        }
        protected string GetMarkers()
        {
            string markers = "";
            int c = 1;
            foreach (GridViewRow grdRow in grdLocations.Rows)
            {
                markers +=
                    @"var marker" + c + @" = new google.maps.Marker({
                    position: new google.maps.LatLng(" + grdRow.Cells[1].Text.ToString() + ", " +
                    grdRow.Cells[2].Text.ToString() + ")," +
                    @"map: myMap,
                    title:'" + grdRow.Cells[0].Text.ToString() + "'});";
                c++;
            }
            return markers;
        }
    }
}