run demo.py and have a error

Traceback (most recent call last):
File "../../tools/demo.py", line 56, in
state = siamese_track(state, im, mask_enable=True, refine_enable=True) # track
File "/home/zhouwenzhang/SiamMask-master/tools/test.py", line 254, in siamese_track
mask = net.track_refine((delta_y, delta_x)).cuda().sigmoid().squeeze().view(
File "/home/zhouwenzhang/SiamMask-master/experiments/siammask/custom.py", line 157, in track_refine
pred_mask = self.refine_model(self.feature, self.corr_feature, pos=pos)
File "/opt/conda/envs/pytorch-py3.6/lib/python3.6/site-packages/torch/nn/modules/module.py", line 468, in __call__
result = self.forward(*input, **kwargs)
File "/home/zhouwenzhang/SiamMask-master/experiments/siammask/custom.py", line 123, in forward
out = self.post0(F.upsample(self.h2(out) + self.v2(p2), size=(31, 31)))
File "/opt/conda/envs/pytorch-py3.6/lib/python3.6/site-packages/torch/nn/functional.py", line 1797, in upsample
return torch._C._nn.upsample_nearest2d(input, _scale_factor(2))
File "/opt/conda/envs/pytorch-py3.6/lib/python3.6/site-packages/torch/nn/functional.py", line 1769, in _scale_factor
'x'.join(map(str, input.size()))))
RuntimeError: output size specified in UpsamplingNearest (31x31) has to be divisible by the input size, but got: 1x32x15x15