ASP.NET SlideShowExtender从web服务检索图像，但在执行时不执行任何操作

因此，在我的ASP.NET解决方案的默认页面上，我有一个SlideShowExtender对象，链接到从MSSQL数据库检索幻灯片的WebMethod。通过调试，我可以确认Slide对象是从所述数据库中成功创建的，但一旦页面加载，SlideShow元素就什么都不做了。

下面是我的代码；我感谢事先收到的任何回复。非常感谢。

编辑：我忘了提到我已经验证了图像URL的完整性；它们是正确的。

Default.aspx（Default.aspx只是一个带有空Page_Load方法的标准代码）：

<%@ Page Title="Home Page" Language="C#" MasterPageFile="~/Site.master" AutoEventWireup="true"
CodeBehind="Default.aspx.cs" Inherits="Dissertation._Default" %>
<%@ Register Assembly="AjaxControlToolkit" Namespace="AjaxControlToolkit" TagPrefix="asp" %>
<asp:Content ID="HeaderContent" runat="server" ContentPlaceHolderID="HeadContent">
</asp:Content>
<asp:Content ID="BodyContent" runat="server" ContentPlaceHolderID="MainContent">
<asp:ToolkitScriptManager ID="scrptman" runat="server"></asp:ToolkitScriptManager>
        <asp:Image ID="imgBanner" Width="800" Height="300" runat="server"/>
        <br />
        <asp:Label ID="lblDesc" runat="server"></asp:Label>
        <asp:SlideShowExtender ID="sldShow" runat="server"   
        TargetControlID="imgBanner" 
        SlideShowServicePath="~/BannerImages.asmx"
        SlideShowServiceMethod="GetPhotos"   
        AutoPlay="true"    
        ImageDescriptionLabelID="lblDesc" 
        Loop="true" />
</asp:Content>

BannerImages.asmx.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.Services;
using System.Data.SqlClient;
using System.Configuration;
using AjaxControlToolkit;
namespace Dissertation
{
/// <summary>
/// Summary description for BannerImages
/// </summary>
/// 
[System.Web.Script.Services.ScriptService]
[WebService(Namespace = "http://tempuri.org/")]
[WebServiceBinding(ConformsTo = WsiProfiles.BasicProfile1_1)]
[System.ComponentModel.ToolboxItem(false)]
public class BannerImages : System.Web.Services.WebService
{
    [WebMethod]
    [System.Web.Script.Services.ScriptMethod]
    public Slide[] GetPhotos()
    {
        List<Slide> images = new List<Slide>();
        ConnectionStringSettings settings = System.Configuration.ConfigurationManager.ConnectionStrings["Database"];
        SqlConnection conn = new SqlConnection(settings.ConnectionString);
        SqlCommand cmd = new SqlCommand("Select * from sol_bannerData", conn);
        SqlDataReader read = null;
        try
        {
            conn.Open();
            read = cmd.ExecuteReader();
            while(read.Read())
            {
                images.Add(new Slide(Server.MapPath("~/cms/uploads/banners/" + read["ImageURL"].ToString()), "", read["Description"].ToString()));
            }
        }
        catch(SqlException err)
        {
            images.Clear();
            images.Add(new Slide("", "", "Images could not be loaded: " + err.Message));
            return images.ToArray();
        }
        finally
        {
            if(read != null) read.Close();
            if(conn != null) conn.Close();
        }
        Slide[] toReturn = images.ToArray();
        return toReturn;


    }
}
}