Using webform-form-[nid].tpl.php to change default template
Have you made a clear cache in admin/config/development/performance?

Or have you looked if in the template there is a error in the code? To verify this you can try to copy all code of "webform-form.tpl.php" in your "webform-form-23.tpl.php" and at the top of the code, before the first TEST!!! , refresh the cache and look if TEST!!! is displayed. If you display TEST!!! in your previous code there is an error.