Are you getting those nasty errors popping up on your sitemap page? Actually, those are only warnings and will not affect the operation of SiteMap, but I can show you how to fix it.

1. Open the main component file, sitemap.php. This can be found in the original zip file (sitemap20.zip). Look for this line:  defined('_VALID_MOS') or die('Direct Access to this location is not allowed.');
   Directly after this line add : error_reporting(0);
2. Then save the file and upload to  components/com_sitemap/
3. Check that the errors have disappeared and that the component is still working properly.