convert to onnx failed

[ztpaul]

Traceback (most recent call last):
File "/mnt/hgfs/vmshare/myssd/to_onnx.py", line 17, in
torch.onnx.export(net, dummy_input, "myssd.onnx")
File "/home/ballzb/.local/lib/python3.6/site-packages/torch/onnx/init.py", line 148, in export
strip_doc_string, dynamic_axes, keep_initializers_as_inputs)
File "/home/ballzb/.local/lib/python3.6/site-packages/torch/onnx/utils.py", line 66, in export
dynamic_axes=dynamic_axes, keep_initializers_as_inputs=keep_initializers_as_inputs)
File "/home/ballzb/.local/lib/python3.6/site-packages/torch/onnx/utils.py", line 416, in _export
fixed_batch_size=fixed_batch_size)
File "/home/ballzb/.local/lib/python3.6/site-packages/torch/onnx/utils.py", line 279, in _model_to_graph
graph, torch_out = _trace_and_get_graph_from_model(model, args, training)
File "/home/ballzb/.local/lib/python3.6/site-packages/torch/onnx/utils.py", line 236, in _trace_and_get_graph_from_model
trace_graph, torch_out, inputs_states = torch.jit._get_trace_graph(model, args, _force_outplace=True, _return_inputs_states=True)
File "/home/ballzb/.local/lib/python3.6/site-packages/torch/jit/init.py", line 277, in _get_trace_graph
outs = ONNXTracedModule(f, _force_outplace, return_inputs, _return_inputs_states)(*args, **kwargs)
File "/home/ballzb/.local/lib/python3.6/site-packages/torch/nn/modules/module.py", line 532, in call
result = self.forward(*input, **kwargs)
File "/home/ballzb/.local/lib/python3.6/site-packages/torch/jit/init.py", line 360, in forward
self._force_outplace,
File "/home/ballzb/.local/lib/python3.6/site-packages/torch/jit/init.py", line 347, in wrapper
outs.append(self.inner(*trace_inputs))
File "/home/ballzb/.local/lib/python3.6/site-packages/torch/nn/modules/module.py", line 530, in call
result = self._slow_forward(*input, **kwargs)
File "/home/ballzb/.local/lib/python3.6/site-packages/torch/nn/modules/module.py", line 516, in slow_forward
result = self.forward(*input, **kwargs)
File "/mnt/hgfs/vmshare/myssd/ssd_mobilenetv2.py", line 128, in forward
self.priors.type(type(x.data)) # default boxes
File "/mnt/hgfs/vmshare/myssd/ssd_mobilenetv2.py", line 172, in my_detect
ids, count = nms(boxes, scores, nms_thresh, top_k)
File "/mnt/hgfs/vmshare/myssd/layers/box_utils.py", line 194, in nms
keep = scores.new(scores.size(0)).zero().long()
TypeError: expected Float (got Long)