Adding posts_nav_link() to theme

I’m struggling to add posts_nav_link() to index.php. I get no error message, but nothing the nav links don’t appear. What am I missing?

My code looks like this:

`<?php endwhile; else: ?>
<?php posts_nav_link(); ?>
<? // php _e(‘Sorry, no posts matched your criteria.’); ?>
<?php endif; ?>`

The theme I’m using did not have posts_nav_link(); beforehand, perhaps because it has the following just before the endwhile:

`<p class=”post-footer align-right”>
” rel=”bookmark” class=”readmore”>Read more
” class=”comments”><?php comments_number(‘No Comments’, ‘Comments (1)’, ‘Comments (%)’ );?>
<span class=”date”><?php the_time(‘M j, Y’); ?></span>
<?php if ((function_exists(‘get_the_tags’)) ) { the_tags(); } ?></p>`

Thats just a guess. Any ideas? Site is oldworldwandering.com