Can't get this work :(

Hello,

I can’t get this plugin work in the follow, (or this plugin will not help on such):

Created two post types: ‘fruits’, ‘flowers’, that share the same taxonomy ‘colors’.

I would like to browse all itens in alfa/date order (or anything), as long all itens are acessible in the post navigation. When viewing a post ‘fruit’ I’m able to browse the next/previous withint this type, but not the ‘flower’ type.

Tried replacing them nav functions with the plugin functions in single-fruit.php and single-flower.php with no luck, the nav link just don’t show up.

Thanks for any help.

The theme nav code in use:

<nav class="single-post-pagenation row">

<?php if( get_previous_post() ) : ?>
<span class="prev-link">
<?php previous_post_link('%link', __( 'Previous', 'mm_lang' )) ?></span>
<?php endif; ?>

<span class="back-link"><a href="<?php bloginfo('url'); ?>/nucleo"><?php _e('Back to lists', 'mm_lang'); ?></a>
</span>

<?php if( get_next_post() ) : ?>
<span class="next-link"><?php next_post_link('%link', __( 'Next', 'mm_lang' )) ?>
</span>
<?php endif; ?>
</nav>

http://wordpress.org/extend/plugins/previous-and-next-post-in-same-taxonomy/