I am trying xoops on a test site before production

I have a problem with a RSS http://www.atih.sante.fr/feed.rss.php

when i try to configure I have the message in french :
"Echec de la sauvegarde des donn馥s pour la base de donn馥 du flux headline ATIH XmlParse error: not well-formed (invalid token) at line 3
"

The RSS is Encoded in ISO-8859-15 the normal Charset for France. As you post, i have try to modify
headlinerenderer.php and replacing all WINDOWS-1251 by ISO-8859-15
and in admin.php _AM_ENCODINGS but it locks the site.

So the two question, is it only a charset problem, and if it is how to modify for the different charset.

Thanks