I setup 2 sitemaps for the 2 languages of my site.
The default (French) sitemap is OK
https://www.see.asso.fr/sitemap.xml
The second (english) sitemap fails on search engines submission
https://www.see.asso.fr/en/sitemap.xml
They seem both OK when opening in a browser.
However, the english one does not validate when parsed by Google or W3C check.
These tools do not get the xml substance at all, but a Drupal HTML page !
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN""http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" lang="en" xml:lang="en">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>Page not found | SEE</title>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<link rel="shortcut icon" href="/sites/see.asso.fr/files/faviconsee.ico" type="image/x-icon" />
<link type="text/css" rel="stylesheet" media="all" href="/sites/www.see.asso.fr/files/advagg_css/css_807c609e25b3c082ebd7cebe09a28dd0_1.css" />
<link type="text/css" rel="stylesheet" media="all" href="/sites/www.see.asso.fr/files/advagg_css/css_85b5177c9e87f19847e7c8d7c630d951_4.css" />
<link type="text/css" rel="stylesheet" media="all" href="/sites/www.see.asso.fr/files/advagg_css/css_5396d2494e5a7d0272322a3dab96ed4f_4.css" />
<link type="text/css" rel="stylesheet" media="all" href="/sites/www.see.asso.fr/files/advagg_css/css_1370c9b53389c759bdbaefe02e561de3_4.css" />
<link type="text/css" rel="stylesheet" media="all" href="/sites/www.see.asso.fr/themes/fusion/fusion_core/css/grid16-fluid.css" />
<!--[if IE 8]>
<link type="text/css" rel="stylesheet" media="all" href="/sites/www.see.asso.fr/themes/fusion/fusion_core/css/ie8-fixes.css" />
<link type="text/css" rel="stylesheet" media="all" href="/sites/www.see.asso.fr/themes/acquia_prosper/css/ie8-fixes.css" />
<![endif]-->
<!--[if IE 7]>
<link type="text/css" rel="stylesheet" media="all" href="/sites/www.see.asso.fr/themes/fusion/fusion_core/css/ie7-fixes.css" />
<link type="text/css" rel="stylesheet" media="all" href="/sites/www.see.asso.fr/themes/acquia_prosper/css/ie7-fixes.css" />
<![endif]-->
<!--[if lte IE 6]>
<link type="text/css" rel="stylesheet" media="all" href="/sites/www.see.asso.fr/themes/fusion/fusion_core/css/ie6-fixes.css" />
<link type="text/css" rel="stylesheet" media="all" href="/sites/www.see.asso.fr/themes/acquia_prosper/css/ie6-fixes.css" />
<![endif]-->
<link type="text/css" rel="stylesheet" media="all" href="/sites/www.see.asso.fr/themes/acquia_prosper/css/local.css" />
<script type="text/javascript" src="/sites/all/modules/labjs/labjs.min.js"></script>
<script type="text/javascript">
<!--//--><![CDATA[//><!--
var $L = $LAB.setGlobalDefaults({AlwaysPreserveOrder:true});
//--><!]]>
</script>
<script type="text/javascript">
...What's wrong?
Thanks for help