关于onnx转rknn时loading model失败的问题

hello，我自己训练了一个pytorch-efficientNet，转换为onnx以后，onnx2rknn遇到类似的错误，请教一下，如何解决的？

报错如下：
  * https://github.com/tensorflow/addons
If you depend on functionality not listed there, please file an issue.

/home/air/.local/lib/python3.6/site-packages/onnx_tf/common/__init__.py:87: UserWarning: FrontendHandler.get_outputs_names is deprecated. It will be removed in future release.. Use node.outputs instead.
  warnings.warn(message)
--> config model
done
D Save log info to: ./e.log
E Catch exception when loading onnx model: efficient-b0-140.onnx!
E Traceback (most recent call last):
E   File "rknn/api/rknn_base.py", line 343, in rknn.api.rknn_base.RKNNBase.load_onnx
E   File "rknn/base/RKNNlib/converter/convert_onnx.py", line 523, in rknn.base.RKNNlib.converter.convert_onnx.convert_onnx.__init__
E   File "rknn/base/RKNNlib/converter/convert_onnx.py", line 527, in rknn.base.RKNNlib.converter.convert_onnx.convert_onnx.__init__
E   File "rknn/base/RKNNlib/converter/onnx_util.py", line 154, in rknn.base.RKNNlib.converter.onnx_util.ONNXProto_Util.optim_model
E   File "/home/air/.local/lib/python3.6/site-packages/onnx/optimizer.py", line 55, in optimize
E     optimized_model_str = C.optimize(model_str, passes)
E IndexError: _Map_base::at
Load model failed!