Custom Post Type, Taxonomy and Permalinks

Hi

I created a plugin to set a custom post type and a custom taxonomy.
Custom Post Type = Book
Custom Taxonomy = Genre
Custom Terms = Fantasy, Horror

I would like to set these permalinks:
– mydomain.com/books (to list all the posts with book as post type)
– mydomain.com/books/fantasy (to list all the books using the term fantasy)
– mydomain.com/books/the-hobbit (to show the individual post of the book “the-hobbit”)

It’s slighly like this topic, except that for me mydomain.com/books is working, mydomain.com/books/fantasy is working and it’s mydomain.com/books/the-hobbit which is not working. If I list all my posts & books on my homepage, the link is correctly generated but I get a 404 error if I go on the page.

I followed this tutorial but it’s not working

My code:

function wptuts_custom_tags() {
    add_rewrite_rule("^books/([^/]+)/([^/]+)/?",'index.php?post_type=book&genre=$matches[1]&book=$matches[2]','top');
}
add_action('init','wptuts_custom_tags');  

//CREATE CUSTOM TAXONOMIES

function create_books_taxonomies(){
	$labels = array(
		'name' => 'Book Genre',
		'add_new_item' => 'Add New Book Genre',
		'new_item_name' => 'New Book Genre'
	);

	$args = array(
		'labels' => $labels,
		'show_ui' => true,
		'hierarchical' => false,
		//'rewrite' => true,
		'rewrite' => array(
			'slug'=>'books',
			'with_front'=>'false'
		),
		'show_tagcloud' => true
	);
	register_taxonomy( 'genre', 'books', $args);
}

add_action( 'init', 'create_books_taxonomies');

// CREATE CUSTOM POST TYPES

function create_book()
{
	$labels = array(
		'name' => 'Books',
		'singular_name' => 'Book',
		'add_new' => 'Add New',
		'add_new_item' => 'Add New Book',
		'edit' => 'Edit',
		'edit_item' => 'Edit Book',
		'new_item' => 'New Book',
		'view' => 'View',
		'view_item' => 'View Book',
		'search_items' => 'Search Books',
		'not_found' => 'No Books found',
		'not_found_in_trash' => 'No Books found in Trash',
		'parent' => 'Parent Book'
	);  

	$args = array(
		'labels' => $labels,
		'public' => true,
		'menu_position' => 15,
		'supports' => array( 'title', 'editor', 'comments', 'thumbnail',  ),
		'rewrite' => array(
			'slug'=>'books',
			'with_front'=> false,
			'feed'=> true,
			'pages'=> true
		),
		'has_archive'=>true,
		'query_var' => true
	);
	register_post_type( 'books', $args);
}
add_action( 'init', 'create_book' );

function wptuts_book_link( $post_link, $id = 0 ) {
    $post = get_post($id);  

    if ( is_wp_error($post) || 'book' != $post->post_type || empty($post->post_name) )
        return $post_link;  

    // Get the genre:
    $terms = get_the_terms($post->ID, 'genre');
    if( is_wp_error($terms) || !$terms ) {
        $genre = 'uncategorised';
    } else {
        $genre_obj = array_pop($terms);
        $genre = $genre_obj->slug;
    }
	return home_url(user_trailingslashit( "books/$post->post_name" ));
}
add_filter( 'post_type_link', 'wptuts_book_link' , 10, 2 );  

// --- FLUSH ---
function wptuts_plugin_activation() {
    create_book();
    flush_rewrite_rules();
}
register_activation_hook( __FILE__, 'wptuts_plugin_activation');  

function wptuts_plugin_deactivation() {
    flush_rewrite_rules();
}
register_activation_hook( __FILE__, 'wptuts_plugin_activation'); 

add_action('admin_init', 'flush_rewrite_rules');

Do you know what could be wrong or if I should use another solution?
Thank you