user_trader.ReqQryInstrument("",0) get error

[softbug123]

File "C:\Program Files (x86)\Microsoft Visual Studio\Shared\Python36_64\lib\site-packages\ctpwrapper\Trader.py", line 279, in ReqQryInstrument
return super(TraderApiPy, self).ReqQryInstrument(pQryInstrument, nRequestID)
File "ctpwrapper\TraderApi.pyx", line 502, in ctpwrapper.TraderApi.TraderApiWrapper.ReqQryInstrument
TypeError: invalid type

how to solve it?

[softbug123]

另外订购数据以后，没数据被回调。
a = md.SubscribeMarketData(["IF1912"])
请问怎么回事呢

[qytz]

好像 README 里有一节说明：

sometimes quote the market futures data, but there is no trading data from the API stream, better just add time.sleep(2) func call after Init() method invoked, this could help to solve no data response issue.