Customizer.js does not load

Hey guys,
I’ve walked through this tutorial: http://codex.wordpress.org/Theme_Customization_API

And I added the last script: Sample Theme Customization Class

But this part :

public static function live_preview() {
      wp_enqueue_script(
           'mytheme-themecustomizer', // Give the script a unique ID
           get_template_directory_uri() . '/assets/js/theme-customizer.js', // Define the path to the JS file
           array(  'jquery', 'customize-preview' ), // Define dependencies
           '', // Define a version (optional)
           true // Specify whether to put in footer (leave this true)
      );
   }

does not seem to load the theme-customizer.js script.

It’s been two days now, and I don’t know how to fix it 🙁