redirect not working

this is my htaccess :
<IfModule mod_rewrite.c>
RewriteEngine on
RewriteBase /
RewriteCond $1 !^(index\.php|images|img|js|sexyimages|media|roleimages|lang|uploads|files|profile|audio|video|videoplayer|talentimages|captcha|gmap|timthumb|include|ckeditor|webfonts|player|robots\.txt|css|sitemap\.xml|sitemap\.html|BingSiteAuth\.xml)
RewriteRule ^(.*)$ ./index.php/$1 [L]

</IfModule>

and this is my admin login code
<?php if ( ! defined('BASEPATH')) exit('No direct script access allowed');

class Home extends CI_Controller {



function __construct()
{
// Call the Model constructor
parent::__construct();
$this->load->model('admin/adminloginmodel','', TRUE);
$this->load->library('session');
}

public function index()
{
//$objResponse=new xajaxResponse();
$this->load->helper('url');
$data['msg']= '';
if(isset($_POST['submit']))
{

$msg=$this->adminloginmodel->check_adminlogin();
//echo $msg;
if($msg != 'success')
{
//redirect('admin/dashboard', 'refresh');
$data['msg']= $msg;
}
else
{
redirect(site_url('admin/dashboard'));

}

}

$this->load->view('admin/adminhome_view',$data);
}
}

/* End of file home.php */
/* Location: ./application/controllers/home.php */