[Plugin: OptionTree] custom post types created via Option Tree

My sites theme uses Option Tree to create custom post types(cpt). i am using the register_taxonomy_for_object_type function to register the ‘post’ categories to the cpt’s but it is not working. is there something different in the manner that Option Tree creates the cpt that wouldn’t allow the function to register the post categories?

http://ww.wp.xz.cn/extend/plugins/option-tree/