small error in running multi-layer neural network

[adaliu1]

During running the "multilayer_supervised" in matlab, I got an error as below:

Reference to non-existent field 'W'.
Error in stack2params (line 31)
assert(mod(size(stack{d+1}.W, 2), size(stack{d}.W, 1)) == 0, ...
Error in supervised_dnn_cost (line 85)
[grad] = stack2params(gradStack);
Error in minFunc (line 314)
[f,g] = funObj(x,varargin{:});
Error in run_train (line 45)
[opt_params,opt_value,exitflag,output] = minFunc(@supervised_dnn_cost,...

It seems that the error came from the ''stack2params.m''. But I do not find out where the error is in the code. I used the ''stack2params.m'' directly and do not make any modification. Is there any modification be needed? Could anyone help me with this out? Thank you so much.