Primary menu

Hy,
I’me using “thematic” theme with “responsive base” starter child theme.
I tried to add a home link on the menu with this hook :

function childtheme_menu_add_args($args) {
    $blog_title = get_bloginfo();
    $args = array(
        'theme_location' => 'primary-menu',
        'show_home' =>  $blog_title,
        'sort_column' => 'menu_order',
        'menu_class' => 'menu',
        'echo' => true
    );
    return $args;
}
add_filter('wp_page_menu_args','childtheme_menu_add_args');

but nothing happens.
When i use the hook within any menu created in WP, the hook works fine.
When i add a menu in WP in primary, nothing happens.

it’s like the ‘theme_location’ isn’t active.

Thanks for help …