Thank you, I couldn't understand what you meant :-D
In case somebody will come back here to check this problem, I will try to tell what happened.
wp_enqueue_script('wp-postratings', plugins_url('wp-postratings/postratings-js.js'), array('jquery'), '1.63', true);
The last "true" argument indicates so.
In order to be loaded in the footer, it needs a hook to grab... that hook is what atul1280 mentions, the "wp_footer()" hook.
In my case, I didn't have the piece of code...