淘宝API 添加上传商品图片

/// <summary>
     /// 添加商品图片
     /// </summary>
     public void getShopImage() {
         string fileName = Server.MapPath("tp" + DateTime.Now.ToString("yyyyMMddHHmmss") + "-" + DateTime.Now.Millisecond + ".jpg");
         fuImage.SaveAs(fileName);
         string strXml = string.Empty;
         Dictionary<string, string> param = new Dictionary<string, string>();
         param.Add("id","003");//图片id
         param.Add("num_iid", "7962992576");//商品id
         param.Add("properties", "2");
         Dictionary<string, FileItem> param3 = new Dictionary<string, FileItem>();
         param3.Add("image", new FileItem(new System.IO.FileInfo(fileName)));
         strXml = TopAPI.Post("taobao.item.img.upload", Client.Session, param, param3);
          Parser parse3 = new Parser();
         PropImgResponse img = new PropImgResponse();//返回结果
         ErrorRsp shoperr = new ErrorRsp();//错误消息对象
         parse3.XmlToObject2(strXml, "item_img_upload", "item_img/url", img, shoperr);
         if (shoperr.IsError == true)
         {
             ScriptManager.RegisterClientScriptBlock(Page, typeof(Page), "error", string.Format("alert(\"添加图片发生错误！\\r错误代码：{0}\\r错误原因：{1}\\r错误描述：{2}-{3}\");", shoperr.code, shoperr.msg, shoperr.sub_code, shoperr.sub_msg), true);
         }
     }
以上代码是传不上去的，缺少app_key   session   是否传的正确
 添加即可。