สอบถาม Error ของ codeigniter ครับ แนะนำด้วยครับผมเพิ่งจะทดลองใช้ครับ

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

class Job extends CI_Controller {

	function __construct(){
		parent::__construct();
		$this->load->model('department_model', 'department');
	}
	
	public function index()
	{
		$this->load->view('welcome_message');
	}
	
	public function job_add()
	{
		$Content['rs_department'] = $this->department->select_all();
		$data['Content'] = $this->load->view('job_add_view', $Content, true);
		$this->load->view('template', $data);
	}
	
	public function job_add_operate()
	{
		$data = array(
				'job_name'=>$this->input->post('job_name'),
				'job_detail'=>$this->input->post('job_detail'),
				'member_add_id'=>$this->session->userdata('member_id'),
				'depart_id'=>$this->input->post('depart_id'),
				'job_add_date'=>date('Y-m-d H:i:s')
		);	
		$result = $this->db->insert('tbl_jobs', $data);
		if($result)redirect('job/job_add');
	}
}

<?php if( !define('BASEPATH')) exit('No direct script access allowed');
class Department_model extends CI_model{
	function __construct(){
		parent::__construct();
	}
	function select_all(){
		$this->db->select('*');
		return $this->db->get('tbl_department');
	}
}

A PHP Error was encountered

Severity: Warning

Message: Cannot modify header information - headers already sent by (output started at E:\www\helpdesk2\application\models\department_model.php:1)

Filename: helpers/url_helper.php

Line Number: 542