[Koha] No results with the advanced search

Hi everybody, I'm working in a small library and we have installed koha version 16.11.03, but we are having some problems with the search. We only recover information when we use the itemsearch. Whenever we use the advanced search we get no results at all, regardless the term we use (title, author, subject, keyword, etc). The message we get is this: No results found No results match your search for 'ti,wrdl: manual' in Biblioteca catalog. What are we doing wrong? Can anyone please help us? Many thanks in advance, Vanda