Base_url() code not working

I'm creating a CRUD basic application using CodeIgniter. I have created a link for "Insert New User", and within the href of the anchor tag I specified the base url along with the controller name and function name. The code is as below.

PHP Code:

<a href="<?php echo base_url();?>index.php/user/add_form">Insert New User</a> 


config.php code

Code:

$config['base_url']    = 'http://localhost/crudcodeig/';

my controller- users.php

PHP Code:

class Users extends CI_Controller
    {
         public function add_form()
        {
            $this->load->view('insert');
        }
         } 


The problem is I can't view the link specified within the a href. Help is appreciated. Thanks!