Thnaks a lot, it works perfectly fine now!!
I am just wondering a last thing.
My forum is part of a site that will contain html pages (homepage, some presentations, and vidéos) and I would like to know if there is a way (manually off course, I am not asking for a new mod) to had theire urls in the output sitmap file, followwing the same way thay are presented in it.
I imagine there is a place to paste the hard code somewhere in the sitemap.php in order to have this part always displayed on the top of the output file (or maybe within a separate tpl file containning the hard part of the site map to be included at the top of the output file).
And again my problem is that I have now clue about how to do this. I understand it's not really what's your mod uposed to do, but this could usefull to all site like mine.
Thanks a lot for your great job