How to display content underneath post content (single.php)

I’m trying to add a banner image underneath my posts on single.php (after the comments), but nothing is showing up, not even sample text. Here’s the relevant code:

<?php twentythirteen_post_nav(); ?>
				<?php comments_template(); ?>
			<?php endwhile; ?>

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

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

Any suggestions? I’m using Twenty Thirteen