halben on "custom login/logout item to menu"

Wondering if anyone can help me on this:

I have the following:

/*
 * -------------------------------
 * custom_login_out_item_to_menu()
 * -------------------------------
 */

add_filter('wp_nav_menu_items', 'custom_login_out_item_to_menu', 50, 2);
function custom_login_out_item_to_menu($items, $args) {
	if (is_admin() || $args -> theme_location != 'top')
		return $items;

	$redirect = ( is_home()) ? false : get_permalink();

	if (is_user_logged_in())
		$link = '<a href="' . wp_logout_url($redirect) . '" title="' . __('Logout') . '">' . __('Logout') . '</a>';
	else
		$link = '<a href="' . wp_login_url($redirect) . '" title="' . __('Login') . '">' . __('Login') . '</a>';

	return $items .= '<li id="log-in-out-link" class="menu-item menu-type-link">' . $link . '</li>';
}

I'm trying to add a custom login / logout link through my child theme functions.php. When I paste this into my functions.php, it's suppose to generate a login/logout link in my theme location : Top Navigation.

The problem is, it's now showing anything. Can anyone please help fix this?

Thanks,
Hal