fileupload的问题(提示:未能找到文件......)

Question

vs.net 2005.代码如下:
protected void Button_Download_Click(object sender, EventArgs e)
    {
        if (FileUpload1.HasFile)
        {
            try
            {
                String name = FileUpload1.PostedFile.FileName;
                FileInfo file = new FileInfo(name);
                if (file.Length < 20 * 1024 * 1024)
                {
                    if (IsValidFileType(file.Name))
                    {
                        String savePath = Server.MapPath("~/JwcDownload/" + file.Name);
                        if (!File.Exists(savePath))
                        {
                            FileUpload1.PostedFile.SaveAs(Server.MapPath("~/JwcDownload/") + FileUpload1.FileName);
                            //Page.Response.Write(FileUpload1.PostedFile.ContentType + FileUpload1.PostedFile.ContentLength + "<br>");
                            String str = "insert into JwcDownload(D_FileName,D_ViewName,D_Date) values(@D_FileName,@D_ViewName,@D_Date)";
                            OleDbConnection Connection = new OleDbConnection("Provider=Microsoft.Jet.OLEDB.4.0;Data Source=" + HttpContext.Current.Request.PhysicalApplicationPath + ConfigurationManager.ConnectionStrings["david"]);
                            OleDbCommand cmd = new OleDbCommand(str, Connection);
                            cmd.Connection.Open();
                            cmd.Parameters.AddWithValue("@D_FileName", file.Name.ToString());
                            cmd.Parameters.AddWithValue("@D_ViewName", TextBox1.Text.ToString());
                            cmd.Parameters.AddWithValue("@D_Date", System.DateTime.Now.ToString());
                            cmd.ExecuteNonQuery();
                            Connection.Close();
                            Page.Response.Write("<script language='javascript'>alert('文件上传成功！');window.location='admin_jwcdowload.aspx';</script>");
                        }
                        else
                        {
                            Response.Write("<script>alert('出错了！文件已经存在，请重命名后上传！')</script>");
                        }
                    }
                    else
                    {
                        Response.Write("<script>alert('出错了！上传文件格式不对！')</script>");
                    }
                }
                else
                {
                    Response.Write("<script>alert('出错了！上传文件太大！')</script>");
                }
            }
            catch (Exception ex)
            {
                Response.Write(ex.Message.ToString());
            }
            finally
            {
                FileUpload1.Dispose();
            }
        }
    }    public bool IsValidFileType(string FileName)//文件格式检验
    {
        string ext = FileName.Substring(FileName.LastIndexOf(".") + 1, FileName.Length - FileName.LastIndexOf(".") - 1);
        for (int i = 0; i < AcceptedFileTypes.Length; i++)
        {
            if (ext.ToLower() == AcceptedFileTypes[i])
            {
                return true;
            }
        }
        return false;
    }本机运行一切正常,上传到服务器(WIN 2003)后,上传是总是提示:未能找到文件......
请各位大侠帮帮忙,在线等