issue with sitemap-extended plugin

not sure so I prefer discuss on forum before create a ticket.

with sitemap-extended, I have this xml file /cache_html/sitemap/sitemap-zenphoto-index.xml.
In this file I can see the following code:

<urlset xsi:schemaLocation="http://www.sitemaps.org/schemas/sitemap/0.9 http://www.sitemaps.org/schemas/sitemap/0.9/sitemap.xsd">
    <url>
        <loc>http://www.vincentbourganel.fr</loc>
        <lastmod>2017-10-17T09:46:16Z</lastmod>
        <changefreq>weekly</changefreq>
        <priority>0.9</priority>
    </url>
    <url>
        <loc>http://www.vincentbourganel.fr/page/2</loc>
        <lastmod>2017-10-17T09:46:16Z</lastmod>
        <changefreq>weekly</changefreq>
        <priority>0.9</priority>
    </url>
    <url>
        <loc>http://www.vincentbourganel.fr/page/3</loc>
        <lastmod>2017-10-17T09:46:16Z</lastmod>
        <changefreq>weekly</changefreq>
        <priority>0.9</priority>
    </url>
</urlset>