Custom post type register in wordpress

custom_post_type_register.php

<?php 
function amas_register() {
    $labels = array(
        'name' => _x('AMAs', 'post type general name'),
        'singular_name' => _x('AMAs', 'post type singular name'),
        'add_new' => _x('Add AMA', 'AMAs'),
        'add_new_item' => __('Add New AMA'),
        'edit_item' => __('Edit AMA'),
        'new_item' => __('New AMA'),
        'view_item' => __('View AMA'),
        'search_items' => __('Search AMA'),
        'not_found' =>  __('Nothing found'),
        'not_found_in_trash' => __('Nothing found in Trash'),
        'parent_item_colon' => ''
    );
    $args = array(
        'labels' => $labels,
        'public' => true,
        'publicly_queryable' => true,
        'show_ui' => true,
        'query_var' => true,
        'rewrite'  => array( 'slug' => 'amas', 'with_front' => false ),
//        'rewrite' => true,
        'capability_type' => 'post',
        'hierarchical' => false,
        //'menu_icon'  => '',
        'menu_position' => 8,
        'supports' => array('title','editor','thumbnail','custom-fields')
    ); 
    register_post_type( 'amas' , $args );
    flush_rewrite_rules();
}
add_action('init', 'amas_register');
?>