After several hours workin hard
 I've found that in file dbmodel.php there was a sentence after a setquery(), this sentence (if (JEVHelper::isAdminUser($user))corruted the query and so it was imposible to search. Indeed this instruction do nothing, so it's safe to eliminate and the search option will work fine.
  I've found that in file dbmodel.php there was a sentence after a setquery(), this sentence (if (JEVHelper::isAdminUser($user))corruted the query and so it was imposible to search. Indeed this instruction do nothing, so it's safe to eliminate and the search option will work fine.Regards
