[isf-wifidog] Problem with no English language

[Punto Tecnologico]

May be this is a stupid question but I'm not a LInux skilled user.
I have installed Wifidog auth  on Ubuntu 7.10 (English) and I'm experiencing 
an error when I select a differrent language that English.
This is the error msg shows at the top of screen, before the login page:

Warning in /classes/Locale.php setCurentLocale: Unable to setlocale() to 
parameter: it_IT. I tried it_IT.UTF-8, it_IT, it.UTF-8, it, and got return 
value: , current locale is: C

If I select a different language like French each reference to IT change to 
FR and so...

Thanks for the support

Carlo M.
I W 2 F I V