帮我看一下吧,初学,分也不多!谢谢了!

Question

为什么我的一个判断不起作用呢!程序直接运行第二个判断?int Num = 1;
        if (DateTime.Now.DayOfWeek.ToString() == "saturday")
        {
            Response.Write(" <script>alert('今天是星期六！');;window.location.href='userJiang.aspx'</script> ");
        }
        else
        {
            if (System.Convert.ToInt32(MySQL.ReturnVal("select jifen from users where id=" + ReaderUser(2))) < Num)
            {
                Response.Write("<script>alert('对不起,您的所余积分已经不足兑换您投奖了.')</script>");
            }
            else
            {
                if (MySQL.Execute("insert into toujiang (type,uid,num) values (0," + this.ReaderUser(2) + "," + this.skey.Text.Trim() + ")"))
                {
                    MySQL.Execute("update users set jifen=jifen-" + Num + " where id=" + ReaderUser(2));                    Response.Write("<script>alert('您的投奖内容已经提交成功,请等待结果吧.');window.location.href='userJiang.aspx'</script>");
                }
                else
                    Response.Write("<script>alert('对不起,投奖失败,请稍候再试.');</script>");
            }
        }