各位大哥，帮我看一下这个代码吧？？（在线等待啊！急求！！）

前台：
<%@ Page Language="C#" AutoEventWireup="true" CodeFile="UpImage.aspx.cs" Inherits="admin_MyAlum" %><!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"><!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN" >
<HTML>
  <HEAD>
    <title>多文件上传</title>
    <script language="JavaScript">  function addFile() { var str = '<INPUT type="file" size="50" NAME="File">' document.getElementById('MyFile').insertAdjacentHTML("beforeEnd",str) } </script>
  </HEAD>
  <body>
    <form id="form1" method="post" runat="server" enctype="multipart/form-data">
      <center>
        <asp:Label Runat="server" ID="MyTitle">多文件上传</asp:Label>
        <P id="MyFile"><INPUT type="file" size="50" NAME="File"></P>
        <P id="P1">
          <input type="button" value="增加(Add)" onclick="addFile()">
          <asp:Button Runat="server" Text="上传" ID="Upload" OnClick="Upload_Click"></asp:Button>
          <input onclick="this.form.reset()" type="button" value="重置(ReSet)">
        </P>
      </center>
    </form>
  </body>
</HTML>
后台：
using System;
using System.Data;
using System.Data.SqlClient;
using System.Configuration;
using System.Collections;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;public partial class admin_MyAlum : System.Web.UI.Page
{
    SqlConnection conn = new SqlConnection(System.Configuration.ConfigurationManager.ConnectionStrings["connstring"].ToString());
    SqlCommand comm;
    SqlDataAdapter da;
    DataSet ds;
    protected void Page_Load(object sender, EventArgs e)
    {
        if (!IsPostBack)
        {
            if (Session["name"] == null)
            {
                Response.Redirect("Login.aspx");
            }
        }
    }
    //执行多个文件上传的方法
    private bool upMoerfile()
    {
        bool bo = false;
        bool flag = false;
        //遍历File表单元素
        System.Web.HttpFileCollection files = System.Web.HttpContext.Current.Request.Files;
        int filecount = 0;
        int cnt = files.Count;
        try
        {
            for (filecount = 0; filecount < files.Count; filecount++)
            {
                System.Web.HttpPostedFile postedfile = files[filecount];
                //取得上传文件名
                string fileName, fileExtension;
                fileName = System.IO.Path.GetFileName(postedfile.FileName);
                if (fileName != string.Empty)
                {
                    fileExtension = System.IO.Path.GetExtension(fileName);
                    if (fileExtension != ".gif" && fileExtension != ".jpg" && fileExtension != ".jpeg" && fileExtension != ".bmp" && fileExtension != ".png")
                    {
                        Response.Write("<script language=javascript>alert('文件格式不正确!');</script>");
                        Response.End();
                    }
                    else
                    {
                        postedfile.SaveAs(Server.MapPath("images\\")+fileName);
                        flag = true;
                        bo = SaveImage(fileName);
                        
                    }
                    if (!bo)
                    {
                        Response.Write("<script language=javascript>alert('上传失败!');</script>");
                        Response.End();
                    }
                }
            }
        }
        catch (Exception ex)
        {
            Response.Write("<script language=javascript>alert('上传失败!');</script>");
            Response.End();
        }
        return flag;
    }
    //把要上传的文件名写入数据库中
    private bool SaveImage(string filename)
    {
        bool flag = false;
        //string sql = "insert into UserImageTB values("+id+",'"+filename+"')";
        comm = new SqlCommand();
        if (conn.State == ConnectionState.Closed)
        {
            conn.Open();
        }
        try
        {
            da = new SqlDataAdapter("select * from Users where UserName='" + Session["name"].ToString() + "'", conn);
            da.Fill(ds, "tables");
            if (ds.Tables["tables"].Rows.Count > 0)
            {
                int id = int.Parse(ds.Tables["tables"].Rows[0]["id"].ToString());
                string sql = "insert into UserImageTB values(" + id + ",'" + filename + "')";
                comm = new SqlCommand(sql, conn);
                int cnt = comm.ExecuteNonQuery();
                if (cnt > 0)
                {
                   flag = true;
                }
            }
        }
        catch (Exception ex) { }
        finally
        {
            conn.Close();
        }
        return flag;
    }
    protected void Upload_Click(object sender, EventArgs e)
    {
        bool flag = false;
        flag=upMoerfile();
        if (flag)
        {
            Response.Write("<script language=javascript>alert('上传成功!');</script>");
            Response.End();
        }
        else
        {
            Response.Write("<script language=javascript>alert('上传失败!');</script>");
            Response.End();
        }
    }
}
到底是哪里的问题啊？？？