[Koha] Problem in advanced search

Hi everybody, I have installed Koha 10.5 (UNIMARC) in Centos 6.3 here http://biblio2.berneri.apiedelibero.net/ If I search for (in the normal search box) "kropotkin" I get the result but If I search for the same word in the advaced search, choosing the Library "Biblioteca Circolo Anarchico Berneri", I get no results. I have already talked about this problem in irc without finding a solution. Unfortunately it seems that there aren't useful logs. Please, can someone help me? Thank you in advance, Gio