fatal error ..

class Admin extends CI_Controller {
 
	function __construct(){
 
		parent::__construct();
		$this->load->helper('url');
	}
 
	function index(){
		$data['title']="Shopping Cart";
		$this->load->view('/backend/login_view');
	}
 
	function home(){
		$data['title']="Shopping Cart";
		$data['action']=site_url('');
		$this->load->view('/backend/home_view');
	}
 
	function login() {
 
 
			$this->load->model('login_model');
			$query=$this->db->get('user');
			$username=$this->input->post('username');
			$password=$this->input->post('password');
			$pass=md5($password);
 
			if ($query->num_rows() = 1) {
 
				$data['header']="Hi,".$username;
				$data['user']="Hi,".$username;
				$data['link_loggout']="logout,".$username;
				$newdata=array(
					'username' => $username,
					'password' => '$password',
					'logged_in' => TRUE);
 
				$this->session->set_userdata($newdata);
				redirect('admin/home','refresh');
			} else {
				$data['title']="Shopping Cart";
				$data['header']="<b><font color='blue'> Username dan Password salah</b></font>";
				$this->load->view('/backend/login_view',$data);
			}
	}
}