Using webform-form-[nid].tpl.php to change default template

On drupal 7, using webform 7.x-4.11, I am trying to modify the template of a specific webform.

So, in /web/themes/bartik/templates (I am using bartik theme) I created a file named webform-form-23.tpl.php

As "23" is the nid of my webform. But the template is not applying at all...

If a create a file webform-form.tpl.php it is well applying to all my webforms...