previous_post_link in same taxonomy in custom post type

I’d suggest using a plugin for this. next_post_link and previous_post_link will use the category taxonomy (literally)*, so they will not work as expected with custom taxonomies, which I think you are using here.

I’ve used both Smarter Navigation by Scribu and Ambrosite Next/Previous Post Link Plus, which are both great plugins for this sort of thing.

*See the source for get_adjacent_post() which is used by WP’s next/previous_post functions in \wp-includes\link-template.php to see how “category” is hard-coded.

Hata!: SQLSTATE[HY000] [1045] Access denied for user 'divattrend_liink'@'localhost' (using password: YES)