CodeIgniter:查询未被执行

I'm having a strange issue with codeigniter + postgresql. This is my table:

sLearning=> select * from lezione;
 id |      titolo      | descrizione |    data    | corsoid 
----+------------------+-------------+------------+---------
  1 | prova            |             | 2014-10-09 |    1234
  2 | Lezione di oggi! |             | 2014-10-09 |    1234
(2 rows)

I' have manually inserted these two records to test my queries. Btw, this is inside my model Lezione_m:(I removed some checks and other controls but anyway, even this version is not working:)

public function get_lezione()
{
    echo $this->db->_error_message();
    $query = $this->db->get('lezione');
    return $query->result();
}

This is my controller:

class Test_c extends CI_Controller
{

function __construct() 
{
    parent::__construct();
    $this->load->model('Lezione_m');
}
public function index()
{     

    $this->load->view('test', $data);
    $this->output->enable_profiler(TRUE);
    echo '<pre>';  
        print_r($this->Lezione_m->get_lezione(null, 1234)); 
    echo '</pre>';
}

The print_r:

Array
(
)

What the profiler says about my query:

0.0001      SELECT *
FROM "lezione" 

Not sure what is going on here. I'm pretty sure that codeigniter it's connected to the database ( i would get some kind of error in that case).

Done. It's a strange thing, but site were working but the port number inside the database config file were wrong.