TBPY获取不到数据

Xbt677036

以下是我的的代码，返回的是一个空字典，这是什么原因呢

# -*- coding:utf-8 -*-
import tbpy, datetime


def get_data():
    print(tbpy.init())
    symbols = ['TA000.CZCE']
    freq = '1d'
    begin_time = datetime.datetime.strptime('2019501', '%Y%m%d')
    end_time = datetime.datetime.strptime('20200512', '%Y%m%d')
    bars = tbpy.get_history(symbols, freq, begin_time, end_time)
    print(bars)
    # return bars


if __name__ == '__main__':
    get_data()

# 返回结果
    True
    {}