Oracle数据库恢复数据提示快照过旧怎么解决

flashback table PRD_CASTING_RECORD to timestamp to_timestamp('2016/8/8 12:00:00','yyyy-mm-dd hh24:mi:ss');
执行这条语句时出现上面的提示，请问如何解决

http://www.2cto.com/database/201507/421997.html