I had the following problem:
The sitemap would create an entry in the XML saying:
"/page/subpage"
instead of
"http://www.domain.com/page/subpage".
Google doesn't recognize this. You always need the domain name in the URL.
I've added a little fix to the sitemap PHP script:
$siteurl = get_bloginfo('siteurl');
if (strpos($permalink,$siteurl) === FALSE) {
$permalink = $siteurl . $permalink;
}
Added in line 2214, which is just before:
//Add it
$this->AddUrl($permalink,$this->GetTimestampFromMySql(($post->post_modified_gmt && $post->post_modified_gmt!='0000-00-00 00:00:00'?$post->post_modified_gmt:$post->post_date_gmt)),($isPage?$cf_pages:$cf_posts),$prio);
That solves the issue, in case anyone else had it.