tags not showing on custom post type single page

You cant display tags on a custom post type if that custom post type doesn’t have tags registered. By default the Tags taxonomy is assigned to posts, you will need to register your post type accordingly.

To do so, use the taxonomies parameter:

taxonomies

(array) (optional) An array of registered taxonomies like category or post_tag that will be used with this post type. This can be used in lieu of calling register_taxonomy_for_object_type() directly. Custom taxonomies still need to be registered with register_taxonomy().

Default: no taxonomies

http://codex.wordpress.org/Function_Reference/register_post_type