Unable to load the requested class: �form_validation�

[eluser]Unknown[/eluser]
can any one help with this im in a bit over my head. I have followed this to the letter and it just will not work
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A PHP Error was encountered

Severity: Notice

Message: Use of undefined constant �form_validation� - assumed '�form_validation�'

Filename: controllers/account.php

Line Number: 9
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A PHP Error was encountered

Severity: Notice

Message: Use of undefined constant �session� - assumed '�session�'

Filename: controllers/account.php

Line Number: 9
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A PHP Error was encountered

An Error Was Encountered

Unable to load the requested class: �form_validation�
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This is the code for my controller class
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<?php

class Account extends CI_Controller

{
function __construct()
{
parent::__construct();
$this->load->library (array(‘form_validation’, ‘session’));
$this->load->helper(array(‘url’, ‘form’));
$this->load->model(‘account_model’);

$this->_salt = “123456789987654321”;
}
function index ()
{
if ($this->account_model->logged_in() ===TRUE)
{
$this->dashboard(TRUE);
}
else
{
$this->load->view('account/details');
}
}

function dashboard($condition = FALSE)
{
if ($condition ===TRUE OR $this->account_model->logged_in() ===TRUE)
{
$this->load->view('account/dashboard');
}
else
{
$this->load->view('account/details');
}
}
function login()
{
$this->form_validation->
set_rules('username', 'Username',
'xss_clean|required|callback_username_check');
$this->form_validation->
set_rules ('password', 'Password',
'xss_clean|required|min_length[4]|max_length[12]|
shal|callback_password_check');

$this->_username = $this->input->post('username');
$this->_password =
shal($this->_salt . $this->input->post('password'));
{
if ($this->form_validation->run() ==FALSE)
{
$this->load->view('account/login');
}
else {
$this->account_model->login();

$data ['message'] =
"You are logged in"
. anchor('account/dashboard', 'Dashboard');
$this->load->view('account/success', $data);
}
}

function register()
{
$this->form_validation->
set_rules('username', 'Username', 'xss_clean|required');

$this->form_validation->
set_rules('email', 'Email Address',
'xss_clean|required|valid_email|callback_email_exists');

$this->form_validation->set_rules('password', 'Password', 'xss_clean|required|min_length[4]|max_length[12]|matches[password_conf]
|shal');

$this->form_validation->
set_rules('password_conf', 'Password Confirmation',
'xss_clean|required|matches[password]|shal');

if ($this->form_validation->run() == FALSE)
{
$this->load->view('account/register');
}
else {
$data['username'] = $this->input->post('username');
$data['email'] = $this->input->post('email');
$data['password'] =
shal($this->_salt . $this->input->post('password'));

if ($this->account_model->create($data) ===TRUE)
{
$data['message'] =
"The user account has been successfully created "
. anchor ('account/login', 'here') . ".";
$this->load->view('account/success', $data) ;
}
else {
$data['$error'] =
"There was a problem when creating your account.";
$this->load->view('account/error', $data);
}
}
}

function logout()
{
$this->session->sess_destroy();
$this->load->view('account/logout');
}

function password_check()
{

$this->db->where('username', $this->_username);
$query = $this->db->get('users');
$result = $query->row_array();
if ($result['password'] == $this->_password);
{
return TRUE;
}

if ($query->num_rows() == 0)
{
$this->form_validation->
set_message('password_check', ' There was an error!');
return FALSE;
}

}

function user_exists($user)
{
$query = $this->db->get_where('users', array('username' => $user));

if ($query->num_rows() > 0 )
{
$this->form_validation->
set_message ('user_exists',
'The %s already registered.');
return FALSE;
}

$query->free_result();

return TRUE;
}

function email_exists($email)
{
$query = $this->db->get_where('users', array('email' => $email));

if ($query->num_rows() > 0)
{
$this->form_validation->
set_message ('email_exists',
'the %s is already registered.');
return FALSE;
}

$query->free_result();

return TRUE;
}
}
}
?>