Procedure does not execute in codeigniter

function renovarEmprestimos($matricula, $livro){
$this->db = $this->load->database('biblioteca', TRUE);
$query = $this->db->query("EXEC J_renovarlivroweb '$matricula', '$livro', '1' ");
//$this->db->last_query();
return $query->result();
}

My function was functional but now I can no longer run EXEC by calling the function. However, if you call $ this-> db-> last_query (); and putting EXEC in the sql database works fine. How can I execute this exec by calling the function?