`sign invalid` problem for device logs query. 

The following api request works fine: 
```python
res = openapi.get('/v1.0/iot-03/devices/{}/status'.format(DEVICE_ID))
```

However, when I request for device logs it returns `sign invalid`. 

```
res = openapi.get("/v1.0/iot-03/devices/{}/logs?end_time=9999999999999&start_time=0&event_types=1".format(DEVICE_ID))
```
This is confusing. How to fix this problem? 