Got error when use 2 gpus.

[gtxjinx]

I got an error when I use 2 gpus to train the model on ImageNet. I followed the steps in README, but I got the following error.
Traceback (most recent call last):
File "imagenet.py", line 340, in
main()
File "imagenet.py", line 336, in main
engine.train(h, iter_train, opt.epochs, optimizer)
File "/usr/local/lib/python3.6/site-packages/torchnet/engine/engine.py", line 63, in train
state['optimizer'].step(closure)
File "/usr/local/lib/python3.6/site-packages/torch/optim/sgd.py", line 80, in step
loss = closure()
File "/usr/local/lib/python3.6/site-packages/torchnet/engine/engine.py", line 52, in closure
loss, output = state'network'
File "imagenet.py", line 265, in h
y_s, y_t, loss_groups = utils.data_parallel(f, inputs, params, mode, range(opt.ngpu))
File "/opt/ml/job/utils.py", line 64, in data_parallel
return gather(outputs, output_device)
File "/usr/local/lib/python3.6/site-packages/torch/nn/parallel/scatter_gather.py", line 68, in gather
return gather_map(outputs)
File "/usr/local/lib/python3.6/site-packages/torch/nn/parallel/scatter_gather.py", line 63, in gather_map
return type(out)(map(gather_map, zip(*outputs)))
File "/usr/local/lib/python3.6/site-packages/torch/nn/parallel/scatter_gather.py", line 63, in gather_map
return type(out)(map(gather_map, zip(*outputs)))
File "/usr/local/lib/python3.6/site-packages/torch/nn/parallel/scatter_gather.py", line 55, in gather_map
return Gather.apply(target_device, dim, *outputs)
File "/usr/local/lib/python3.6/site-packages/torch/nn/parallel/_functions.py", line 54, in forward
ctx.input_sizes = tuple(map(lambda i: i.size(ctx.dim), inputs))
File "/usr/local/lib/python3.6/site-packages/torch/nn/parallel/_functions.py", line 54, in
ctx.input_sizes = tuple(map(lambda i: i.size(ctx.dim), inputs))
RuntimeError: dimension specified as 0 but tensor has no dimensions

Thank you if you have any solution to this.