How do I get the Word Press function “wp_link_pages” working?

I purchased a theme and it doesn’t create links to pages when I insert the short tag <!--nextpage-->.

According to the WP Codex I need to have this code:
<?php wp_link_pages(); ?> in The Loop.

Here is the templates index page which contains The Loop:

<div id="the_body">
    <?php dynamic_sidebar(2);  ?>
    <div class="clearboth"></div>

<?php if (get_option('uniq_homepage_content')) { ?>
    <?php wp_reset_query(); ?>
    <?php if(have_posts()) : $scounter=0; ?>
  <?php while(have_posts()) : the_post() ?>
  <?php $scounter++; ?>
  <?php $post_images = wp_get_attachment_image_src( get_post_thumbnail_id(), 'large'); ?>

    <div id="post-<?php the_ID(); ?>" class="posts_small <?php if ($scounter==1) echo 'first_small'; ?>">
        <?php if ($post_images[0]) { ?>
            <a href="<?php the_permalink() ?>" rel="bookmark" title="Permanent Link to <?php the_title_attribute(); ?>" class="preloader"><img src="<?php echo bloginfo('template_url'); ?>/thumb.php?src=<?php echo $post_images[0];?>&w=200&h=200&zc=1&q=80<?php echo $thumb_url;?>" alt="<?php the_title(); ?>"  class="mag fade_hover preloader" /></a>
        <?php } ?>

        <div class="post_content">
            <h2><a href="<?php the_permalink() ?>" rel="bookmark" title="Permanent Link to <?php the_title_attribute(); ?>"><?php the_title(); ?></a></h2>
            <p class="meta">By <?php the_author_posts_link(); ?> | <?php the_time('F j, Y'); ?> at <?php the_time('g:i a'); ?> | <a href="<?php the_permalink(); ?>#commentarea"><?php comments_number('No comments', 'One comment', '% comments'); ?></a></p>
            <p><?php echo bm_better_excerpt(280, '...'); ?></p>
            <p class="tags">Posted in: <span class="category"><?php the_category(", "); ?> </span></p>
        </div>

    </div>  

  <?php endwhile; ?>

    <div class="pagination">
        <?php if (function_exists('wp_pagenavi')) { ?>
            <?php wp_pagenavi(); ?>
        <?php } ?>
    </div>
<?php endif; } ?>
</div> <!-- the_body -->

<?php get_sidebar(); ?>

I put the code snippet in the loop in various place (thinking it might make a difference), but was still not able to get the page links to appear at the bottom of the post.

Is there something in this page that is preventing the wp_link_pages function from working?