据下载失败，触发异常：
Traceback (most recent call last):
File "c:\vnstudio\lib\site-packages\vnpy_ctabacktester\engine.py", line 404, in run_downloading
data = self.datafeed.query_bar_history(req)
File "c:\vnstudio\lib\site-packages\vnpy_tushare\tushare_datafeed.py", line 175, in query_bar_history
freq=ts_interval
File "c:\vnstudio\lib\site-packages\tushare\pro\data_pro.py", line 196, in pro_bar
raise IOError('ERROR.')
OSError: ERROR.
