main_engine = MainEngine() ctp_setting = load_json("connect_ctp.json") main_engine.add_gateway(CtpGateway) main_engine.connect(ctp_setting, "CTP") account_gateway = main_engine.get_gateway("CTP") trade_records = account_gateway.query_contract_delivery()请问大神们为什么trade_records 返回的是None

请问veighna trader 社区版使用SinNow仿真交易账号登陆CTP接口时，出现行情接口报错是什么原因？