请看我的sql 最后用orderby排序居然无效 求解 急！！！
SELECT
*
FROM
(SELECT
INSTITUTIONID,
SYMBOL,
MAX(IF(ENDDATE = '2011-09-30', `EPS`, 0)) AS '2011三季报',
MAX(IF(ENDDATE = '2011-12-31', `EPS`, 0)) AS '2011年报',
MAX(IF(ENDDATE = '2012-03-31', `EPS`, 0)) AS '2012一季报',
MAX(IF(ENDDATE = '2012-06-30', `EPS`, 0)) AS '2012中报'
FROM
STK_FIN_PerShare a
WHERE a.`ENDDATE` BETWEEN '2011-09-30'
AND '2012-06-30'
AND a.`STATETYPECODE` = 'A'
GROUP BY INSTITUTIONID,
SYMBOL
ORDER BY INSTITUTIONID,
ENDDATE ASC) f
ORDER BY '2012中报','2012一季报','2011年报','2011三季报' DESC

(其中EPS是number类型)

[解决办法]
ORDER BY 6 DESC，5 DESC ，4 DESC，3 DESC