mobilenet-ssd v1 模型无法转换

输入节点
    # FeatureExtractor/MobilenetV1/MobilenetV1/Conv2d_0/BatchNorm/FusedBatchNorm
    # FeatureExtractor/MobilenetV1/MobilenetV1/Conv2d_0/BatchNorm/batchnorm/mul_1

    # input
用这仨都是报这个错 但是示例的pb就可以 哪位大神指点一下


--> Building model
Traceback (most recent call last):
  File "ssd.py", line 77, in <module>
    rknn.build(do_quantization=False)
  File "/home/vpi/.local/lib/python3.6/site-packages/rknn/api/rknn.py", line 163, in build
    inputs = self.rknn_base.net.get_input_layers()
AttributeError: 'NoneType' object has no attribute 'get_input_layers'

请教一下，这个问题怎么解决的啊，我也遇到这个问题，谢谢，方便告诉一下吗