jedi-vim: NameError: name 'jedi_vim' is not defined

It’s probably my error somewhere but I cannot install jedi-vim probably because a module is not found; I get this error while doing anything on a .py file:

Error detected while processing function jedi#show_func_def:
line    1:
Traceback (most recent call last):
Press ENTER or type command to continue
Error detected while processing function jedi#show_func_def:
line    1:
File "<string>", line 1, in <module>
Press ENTER or type command to continue
Error detected while processing function jedi#show_func_def:
line    1:
NameError: name 'jedi_vim' is not defined

First I followed this guide: http://redkrieg.com/2012/12/11/writing-python-like-a-jedi/ then I tried installing the jedi module in python directly and importing jedi in python (which worked) but no difference.

I have no other settings about python in vimrc or any other modules.

Any ideas?