并未将物件参考设定为物件的执行个体 这是什麽情况 ，请高手帮忙！！

string userName = txtName.Text.Trim().ToString(); string userPwd = txtpwd.Text.Trim().ToString(); #region //if (txtName.Text == "") //{ // ltDll.ltClass.WebShowMessage("用户名不能为空"); // return; //} //string strSql = string.Format("select * from ltusers where luser =✀ " + userName + "✀ and lpwd=✀"+userPwd+"✀ "); //DataTable dt = ltDll.ltClass.SelectFromMes(strSql); //if (dt.Rows.Count>0) //{ // ltDll.ltClass.WebShowMessage("登陆成功！"); //} // else // { // ltDll.ltClass.WebShowMessage("登陆失败!"); // } #endregion if (userName !="") { string strSql = string.Format("select * from ltusers where luser=✀" + userName + "✀ and lpwd=✀" + userPwd + "✀　"); DataTable dt = ltDll.ltClass.SelectFromMes(strSql); if (dt.Rows.Count>0) { ltDll.ltClass.WebShowMessage("登陆成功！"); } else { ltDll.ltClass.WebShowMessage("用户名和密码不正确！"); } } else { ltDll.ltClass.WebShowMessage("用户名不存在！"); } }