'readObject' function 'load'

[Margrate]

/lua/5.1/torch/File.lua:343: unknown Torch class <nn.ZeroGrad>
stack traceback:
[C]: in function 'error'
.../torch/install/share/lua/5.1/torch/File.lua:343: in function 'readObject'
...
.../torch/install/share/lua/5.1/torch/File.lua:353: in function 'readObject'
.../torch/install/share/lua/5.1/torch/File.lua:369: in function 'readObject'
.../torch/install/share/lua/5.1/nngraph/gmodule.lua:495: in function 'read'
.../torch/install/share/lua/5.1/torch/File.lua:351: in function 'readObject'
.../torch/install/share/lua/5.1/torch/File.lua:409: in function 'load'
/GFRNet/util/util.lua:212: in function 'load'
test.lua:60: in main chunk
[C]: in function 'dofile'
...hare/torch/install/lib/luarocks/rocks/trepl/scm-1/bin/th:150: in main chunk
[C]: at 0x004064f0