Open a webform in colorbox : how to ? [#2091121]

i read about some patch to do on the files module to open a webform in a colorbox window.
what i do:
1- create a webform node / form and get is ID with firebug as :

<form action="/infos-profil-%C3%A9l%C3%A8ve" accept-charset="UTF-8" method="post" id="webform-client-form-419" class="webform-client-form" enctype="multipart/form-data">

2- create a node and add a link into body field as:<a class="colorbox-load" href="/colorbox/form/webform_client_form_419?width=600&height=600">Test colorbox sans iframe avec url relative</a>

3- click on the link and get and empty white window
4- in the dblog 2 messages:

Missing argument 2 for webform_client_form() dans /var/www/drupal6/sites/all/modules/webform/webform.module à la ligne 1741.
Missing argument 3 for webform_client_form() dans /var/www/drupal6/sites/all/modules/webform/webform.module à la ligne 1741.

5- patch 2 module files as explain here :
https://drupal.org/node/940220
6- still there after clear cache and run cron

what can i do more or different to get my webform displayed into colorbox window ?

thanks