Mystique theme uses nav.css and /js/dropmenu.js

Hi, on mystique theme the following is not working (possible is needless), but it throws error on error.log

function add_wp_menu_drop_js_script() {

        wp_enqueue_script('dropmenu', get_template_directory_uri() . '/js/dropmenu.js', array('jquery'));
        wp_enqueue_style('nav', get_template_directory_uri() . '/nav.css', array(), false, 'screen');
    }

   add_action('wp_enqueue_scripts', 'add_wp_menu_drop_js_script');

Custom solution to comment the
// add_action('wp_enqueue_scripts', 'add_wp_menu_drop_js_script');`