问重定向在真实服务器上的Codeigniter中不起作用。在上报告错误，但不显示任何错误

EN

<?php
defined('BASEPATH') OR exit('No direct script access allowed');

class Login_admin extends CI_Controller {

    public function __construct() {
        parent::__construct();

        date_default_timezone_set("Asia/Kolkata");
        $this->load->model('AdminLogin_model');
        $this->load->model('Settings_model');
        $this->load->library('session');

        if($this->session->userdata('logged_in_admin')) { 
            redirect(site_url('bus_details/view_busdetails'));
        }
    }
}
public function index(){

        $template['page_title'] = "Login";
        if(isset($_POST)) {
        $this->load->library('form_validation');

        $this->form_validation->set_rules('username', 'Username', 'trim|required');
        $this->form_validation->set_rules('password', 'Password', 'trim|required|callback_check_database');

        if($this->form_validation->run() == TRUE) {
            // redirect(base_url().'Bus_details/view_busdetails');
            redirect(site_url('bus_details/view_busdetails'));
        }
        }
        $this->load->view('login-form');    
}