./caffe2mdl转换报错Unknownbottomblob'data'

please make sure the input is described as a layer in caffe.prototxt
Unknown bottom blob 'data' (layer 'ConvNdBackward1', bottom index 0)

prototxt:
name: "pytorch"
input: "data"
input_dim: 1
input_dim: 3
input_dim: 256
input_dim: 256

layer {
name: "ConvNdBackward1"
type: "Convolution"
bottom: "data"
top: "ConvNdBackward1"
convolution_param {
num_output: 128
pad_h: 1
pad_w: 1
kernel_h: 4
kernel_w: 4
stride: 2
dilation: 1
}
}
...

该提问来源于开源项目：PaddlePaddle/Paddle-Lite