New installation breaks optim package

[Hugo Alberto Perlin]

Hello,

I re-installed torch using the scripts available in the torch.ch site.
The installation process finished without problems.
But when I try to run a script which uses the optim package an exception occour.
Just for test, the script contents is:

require 'optim'

classes = {1,2}
confusion = optim.ConfusionMatrix(classes)

When a I run using th, there are no errors. But when I run using luajit the result is:

$ luajit testOptim.lua
luajit: /usr/local/share/lua/5.1/torch/init.lua:34: attempt to concatenate a nil value
stack traceback:
/usr/local/share/lua/5.1/torch/init.lua:34: in function 'include'
/usr/local/share/lua/5.1/optim/init.lua:8: in main chunk
[C]: in function 'require'
testOptim.lua:1: in main chunk
[C]: at 0x00404f19

The error occur even if I use $luajit -ltorch testOptim.lua.

Thank you.