Traceback (most recent call last):
File "E:\Software Installation\VNStudio\lib\site-packages\vnpy\trader\ui\mainwindow.py", line 265, in open_widget
widget = widget_class(self.main_engine, self.event_engine)
File "E:\Software Installation\VNStudio\lib\site-packages\vnpy\app\cta_backtester\ui\widget.py", line 43, in init
self.backtester_engine.init_engine()
File "E:\Software Installation\VNStudio\lib\site-packages\vnpy\app\cta_backtester\engine.py", line 60, in init_engine
self.init_rqdata()
File "E:\Software Installation\VNStudio\lib\site-packages\vnpy\app\cta_backtester\engine.py", line 66, in init_rqdata
result = rqdata_client.init()
File "E:\Software Installation\VNStudio\lib\site-packages\vnpy\trader\rqdata.py", line 60, in init
df = rqdata_all_instruments(date=datetime.now())
File "E:\Software Installation\VNStudio\lib\site-packages\rqdatac\decorators.py", line 131, in wrap
return func(args, **kwargs)
File "E:\Software Installation\VNStudio\lib\site-packages\rqdatac\services\basic.py", line 320, in all_instruments
ins_ret = filter(cond, _all_instruments_list(market))
File "E:\Software Installation\VNStudio\lib\site-packages\rqdatac\decorators.py", line 111, in wrapper
value = user_function(args, **kwargs)
File "E:\Software Installation\VNStudio\lib\site-packages\rqdatac\services\basic.py", line 108, in _all_instruments_list
return [Instrument(i) for i in get_client().execute("all_instruments", market=market)]
TypeError: 'NoneType' object is not iterable
