Using Yoast WordPress SEO version 18.104.22.168. with a well tested Yootheme template that has very little customization. The Word Press SEO plugin is enabled and XML sitemap function is enabled. However, the tags page fails to generate. The address of the sitemap is http://www.bpmstr.com/sitemap_index.xml - as you will see, post-sitemap.xml and page-sitemap.xml pages work properly, but post_tag-sitemap.xml link generates a 404 error. I attempted to check/uncheck various combinations of the checkboxes in the Exclude Taxonomies section in the XML Sitemaps area. I also attempted to deactivate sitemaps and to reactivate them. I also attempted to deactivate the plugin and then reactivate it. The result is the same - the page just isn't there. Thanks in advance for your help.