Pagination , Routing 404 - Newbie

Learning CI3  ..... building a simple cms  . Added ' pagination' to the libraries array and tried the code below 

In the posts controller index function i am showing all my posts ( Total of 7 posts of which i try to show 5)  . When i try to use pagination it is showing 404 error 

 ie;  http://localhost/CI3/posts  - shows all 7 posts with pagination links in bottom , clicking '2' takes to http://localhost/CI3/posts/5  which is giving a 404 page not found . 


route.php
------------

PHP Code:

$route['posts/create'] = 'posts/create';
$route['posts/update'] = 'posts/update';
$route['posts/success'] = 'posts/success';
$route['posts'] = 'posts/index';
$route['posts/(:any)'] = 'posts/view/$1';


$route['default_controller'] = 'pages/view';

$route['categories'] = 'categories/index';
$route['categories/create'] = 'categories/create';
$route['categories/posts/(:any)'] = 'categories/posts/$1';


$route['(:any)'] = 'pages/view/$1';
$route['404_override'] = '';
$route['translate_uri_dashes'] = FALSE; 


Posts.php
------------

PHP Code:

Class Posts extends CI_Controller {

    public function index() {

        $data['title'] = 'Latest Posts';

        $config['base_url'] = site_url().'/posts';
        $config['total_rows'] = $this->post_model->count();
        $config['per_page'] = 5;
        //$config['page_query_string'] = TRUE;
        $config['uri_segment'] = 4;

        $this->pagination->initialize($config);

        $data['pagination_links'] = $this->pagination->create_links();

        $data['posts'] = $this->post_model->get_posts();

        $this->load->view('templates/header');
        $this->load->view('posts/index',$data);
        $this->load->view('templates/footer');

    } 


Can somebody help with what went wrong  ..