wp_enqueue_script adding conditional statement not working

This is the code im using in my functions file:

add_action('init', 'sort_out_jquery_pngfix_frontend');
function sort_out_jquery_pngfix_frontend() {
    global $wp_scripts;
    if(!is_admin()) {
        wp_deregister_script('jquery');
        wp_register_script('jquery', 'https://ajax.googleapis.com/ajax/libs/jquery/1/jquery.min.js', array(), NULL, true);
        wp_register_script('dd_belatedpng', get_stylesheet_directory_uri() . '/js/dd_belatedpng.js', array(), NULL, true);
        $wp_scripts->add_data('dd_belatedpng', 'conditional', 'lt IE 7');
    }
}

add_action('wp_print_scripts', 'register_theme_scripts');
function register_theme_scripts() {
    if(!is_admin()) {
        wp_enqueue_script('modernizr', get_stylesheet_directory_uri() . '/js/modernizr-1.7.min.js', array(), NULL, false);
        wp_enqueue_script('googlemaps', 'http://maps.google.com/maps/api/js?sensor=false', array(), NULL, true);
        wp_enqueue_script('jquery');
        wp_enqueue_script('dd_belatedpng');
        wp_enqueue_script('sc_wc_js', get_stylesheet_directory_uri() . '/js/function.js', array('jquery', 'dd_belatedpng'), '1.0', true);
    }
}

I’m using $wp_scripts->add_data('dd_belatedpng', 'conditional', 'lt IE 7'); to add a conditional statement to this script as per the documentation I can find on-line but its not working. The conditional code is not shown but the js file is.

Why is this not working?

From quick look at code this conditional only seems to be processed for styles and not scripts.