编译异常,不包含定义，而且找不到可接受的类型

编译错误,不包含定义，而且找不到可接受的类型。
CS1061: “CS.BLL.LmUserXinXi”不包含“exct”的定义，并且找不到可接受类型为“CS.BLL.LmUserXinXi”的第一个参数的扩展方法“exct”(是否缺少 using 指令或程序集引用?)

以上是错误信息

C# code

    protected void ImageButton1_Click(object sender, ImageClickEventArgs e)    {        CS.BLL.UserInfo bllui = new CS.BLL.UserInfo();        CS.Model.UserInfo uif = new CS.Model.UserInfo();        CS.BLL.LmUserXinXi luxx = new CS.BLL.LmUserXinXi();        CS.Model.LmUserXinXi model = new CS.Model.LmUserXinXi();        bool b = bllui.Existss(YongHuMing.Value.ToString(), MiMa.Value.ToString());        CS.Model.UserInfo UIF = bllui.GetModel(YongHuMing.Value);        userid = UIF.UserID;        if (b){           bool bl = luxx.exct(userid);                        if (bl)            {                model.UserID = userid;                model.NickName = YongHuMing.Value.ToString();                model.ZhangHuLeiXing =1;                model.ZhuangTai = "正常";                CS.Model.LmUserXinXi Model = model;                luxx.Add(Model);                Page.ClientScript.RegisterStartupScript(typeof(Page), "", "alert('登录成功')", true);            }            else             {                Page.ClientScript.RegisterStartupScript(typeof(Page), "", "alert('登录成功')", true);            }                    }        else        {            Page.ClientScript.RegisterStartupScript(typeof(Page), "", "alert('登录失败,账户或密码错误.')", true);        }    }

C# code

        public bool exct(int UserID)         {            return dal.exct(UserID);        }--------------------        /// <summary>        /// 查询用户是否已加入到联盟2011年5月24日        /// </summary>        /// <param name="UserID"></param>        /// <returns></returns>        public bool exct(int UserID)        {            StringBuilder strSql = new StringBuilder();            strSql.Append("select count(1) from LmUserXinXi");            strSql.Append(" where UserID=@UserID");            SqlParameter[] parameters = {                    new SqlParameter("@UserID", SqlDbType.Int)};            parameters[0].Value = UserID;            return DbHelperSQL.Exists(strSql.ToString(), parameters);        }