A simple script to allow sorting of custom posts in admin?

I found this on wordpress.org forums. tested it and works fine. When i changed the variables to my own it failed. I checked it thoroughly (!) for hours. i can’t see where it’s going wrong.

register_post_type( 'book', array(
    'labels' => array(
        'name' => 'Books',
        'singular_name' => 'Book',
        'add_new' => 'Add New',
        'add_new_item' => 'Add New Book',
        'edit_item' => 'Edit book',
        'edit' => 'Edit',
        'new_item' => 'New Book',
        'view_item' => 'View Book',
        'search_items' => 'Search Books',
        'not_found' => 'No books found',
        'not_found_in_trash' => 'No books found in Trash',
        'view' => 'View Book'
    ),
    'public' => true,
    'capability_type' => 'post',
    'hierarchical' => false,
    'rewrite' => true,
    'query_var' => true,
    'supports' => array( 'title', 'editor', 'author', 'thumbnail', 'custom-fields', 'comments' ),
    'taxonomies' => array('category','post_tag')
    )
);
register_taxonomy(
    'book_category',
    'book',
    array(
        'hierarchical' => true,
        'label' => 'Categoriën',
        'public' => true,
        'query_var' => true,
        'show_tagcloud' => true,
        'rewrite' => Array(
            'slug' => 'book_category')
        )
);
function add_new_columns($defaults) {
    $defaults['book_cats'] = __('Categoriën');
    return $defaults;
}
function add_column_data( $column_name, $post_id ) {
    if( $column_name == 'book_cats' ) {
        $_posttype  = 'book';
        $_taxonomy  = 'book_category';
        $terms      = get_the_terms( $post_id, $_taxonomy );
        if ( !empty( $terms ) ) {
            $out = array();
            foreach ( $terms as $c )
                $_taxonomy_title = esc_html(sanitize_term_field('name', $c->name, $c->term_id, 'category', 'display'));
                $out[] = "<a href='edit.php?book_category=$_taxonomy_title&post_type=$_posttype'>$_taxonomy_title</a>";
            echo join( ', ', $out );
        }
        else {
            _e('Uncategorized');
        }
    }
}
add_filter( 'manage_book_posts_columns', 'add_new_columns' );
add_action( 'manage_posts_custom_column', 'add_column_data', 10, 2 ); ?>

My edited version (the newly “adjusted” one that now does something!):

register_post_type( 'frog', array(
    'labels' => array(
        'name' => 'Frog',
        'singular_name' => 'Frog',
        'add_new' => 'Add New',
        'add_new_item' => 'Add New frog',
        'edit_item' => 'Edit frog',
        'edit' => 'Edit',
        'new_item' => 'New frog',
        'view_item' => 'View frog',
        'search_items' => 'Search frogs',
        'not_found' => 'No frogs found',
        'not_found_in_trash' => 'No frogs found in Trash',
        'view' => 'View frog'
    ),
    'public' => true,
    'capability_type' => 'post',
    'hierarchical' => false,
    'rewrite' => true,
    'query_var' => true,
    'supports' => array( 'title', 'editor', 'author', 'thumbnail', 'custom-fields', 'comments' ),
    'taxonomies' => array('category','post_tag')
    )
);
register_taxonomy(
    'frog_category',
    'frog',
    array(
        'hierarchical' => true,
        'label' => 'Categories',
        'public' => true,
        'query_var' => true,
        'show_tagcloud' => true,
        'rewrite' => Array(
            'slug' => 'frog_category')
        )
);
function add_new_frogcolumns($defaults) {
    $defaults['frog_cats'] = __('Categories');
    return $defaults; //missing as pointed out by scribu
}
function add_frogcolumn_data( $column_name, $post_id ) {
    if( $column_name == 'frog_cats' ) {
        $_posttype  = 'frog';
        $_taxonomy  = 'frog_category';
        $terms      = get_the_terms( $post_id, $_taxonomy );
        if ( !empty( $terms ) ) {
            $out = array();
            foreach ( $terms as $c )
                $_taxonomy_title = esc_html(sanitize_term_field('name', $c->name, $c->term_id, 'category', 'display'));
                $out[] = "<a href='edit.php?frog_category=$_taxonomy_title&post_type=$_posttype'>$_taxonomy_title</a>";
            echo join( ', ', $out );
        }
        else {
            _e('Uncategorized');
        }
    }
}
add_filter( 'manage_frog_posts_columns', 'add_new_frogcolumns' );
add_action( 'manage_posts_custom_column', 'add_frogcolumn_data', 10, 2 );//this line was also wrong