Custom Posts Dont show on xml sitemap

Hello,

I have a custom post type ‘exam’ which works fine throughout the site.
On my sitemap_index.xml generated by the yoast plugin, the sitemap sitemap-exam.xml is listed successfully along with all the other sub xml sitemap files relating to each post type etc. The problem is that rather than containing a list of all exam post types published on my site, the sitemap-exam.xml file only contains one link to http://www.ieltsmanchester.co.uk/ielts-exam-practice/%exam_category%/ rather than a list of all exam post type URLs. I have the rewrite rule ‘rewrite’ => array(‘slug’ => ‘ielts-exam-practice/%exam_category%’, ‘with_front’ => false) applied in the register_post_type function which i use in a post_type_link filter to replace that portion of the url with a custom taxonomy I use to assigne each exam to an exam category. I had thought the problem may have been related to this but I’ve also set up a basic custom post type named ‘test’ and the same problem arises. I have checked config numerous times and there doesn’t appear to be any reason why the exam (or test posts) shouldn’t be getting listed.

Any thoughts?

Thanks

http://wordpress.org/plugins/wordpress-seo/