list_devices获取失败

rknn_tool是1.6版本，可以正常import rknn.api，模型转换，但是在连接rk1808进行初始化的时候会报错。Traceback (most recent call last):
  File "/home/gongen/下载/pycharm-profession/pycharm-2020.1.1/plugins/python/helpers/profiler/run_profiler.py", line 173, in <module>
    profiler.run(file)
  File "/home/gongen/下载/pycharm-profession/pycharm-2020.1.1/plugins/python/helpers/profiler/run_profiler.py", line 89, in run
    execfile(file, globals, globals)  # execute the script
  File "/home/gongen/下载/pycharm-profession/pycharm-2020.1.1/plugins/python/helpers/profiler/prof_util.py", line 30, in execfile
    exec(compile(contents+"\n", file, 'exec'), glob, loc)
  File "/home/gongen/pytorch/yolo/run_rknn.py", line 65, in <module>
    rknn.list_devices()
  File "/home/gongen/anaconda3/envs/rknn/lib/python3.6/site-packages/rknn/api/rknn.py", line 336, in list_devices
    adb_devices, ntb_devices = self.rknn_base.list_devices()
  File "rknn/api/rknn_base.py", line 793, in rknn.api.rknn_base.RKNNBase.list_devices
  File "rknn/api/rknn_platform_utils.py", line 350, in rknn.api.rknn_platform_utils.get_ntb_devices
RuntimeError
求助这个怎么解决，每次用rknn模拟跑模型太慢了，谢谢！！！！