unable to view page numbers in posts

Hi guys,

I’ve done as instructed in the installation guideline but unable to get the desired look of page numbers. Could someone point out what I’m doing wrong please? Here’s my code:

<?php
/**
 * The Template for displaying all single posts.
 *
 * @package WordPress
 * @subpackage Twenty_Twelve
 * @since Twenty Twelve 1.0
 */

get_header(); ?>

	<div id="primary" class="site-content">
		<div id="content" role="main">

			<?php while ( have_posts() ) : the_post(); ?>

				<?php get_template_part( 'content', get_post_format() ); ?>

				<nav class="nav-single">
					<h3 class="assistive-text"><?php _e( 'Post navigation', 'twentytwelve' ); ?></h3>
				/*	<span class="nav-previous"><?php previous_post_link( '%link', '<span class="meta-nav">' . _x( '&larr;', 'Previous post link', 'twentytwelve' ) . '</span> %title' ); ?></span>
					<span class="nav-next"><?php next_post_link( '%link', '%title <span class="meta-nav">' . _x( '&rarr;', 'Next post link', 'twentytwelve' ) . '</span>' ); ?></span>*/
<?php wp_pagenavi(); ?>
				</nav><!-- .nav-single -->

				<?php comments_template( '', true ); ?>

			<?php endwhile; // end of the loop. ?>

		</div><!-- #content -->

	</div><!-- #primary -->

<?php get_sidebar(); ?>
<?php get_footer(); ?>

https://www.ads-software.com/plugins/wp-pagenavi/