My sitemap.xml have a different domain and this is an error
I think you have a setting wrong.

Browse to the XML Sitemap settings page (admin/config/search/xmlsitemap/settings).

Expand the Advanced Settings section.

Check/set the Default Base URL.  Typically, I set this to make sure the default base URL gets used, as rebuilding from drush won't set it properly if you don't $uri set in your site alias.