Advanced Custom Fields Plugin - Images not displaying

Question

I am using the ACF purely so the user can upload images to a predefined location and have assigned the page rules accordingly. Everything seems to be fine on the WP back-end, with the three images uploaded to the fields. However, on the font end, nothing apart from blank box is appearing at all where the images should be. Looking at the source that WP is outputting, there is only blank code:

<img src="" class="middle" alt="image1"/>

This is the loop I am using:

<?php query_posts("posts_per_page=1&post_type=page&page_id=168"); if (have_posts()) :  
while ( have_posts() ) :   
the_post(); ?>
<!--If you want to refer to the child of parent page, use "post_parent=" -->
<li>
<h3><?php the_title(); ?></h3>
<?php the_excerpt(); ?>
<img src="<?php the_field('image_1'); ?>" class="middle" alt="image1"/>
<a href="<?php the_permalink(); ?>" class="button">View More</a>
</li>
 <?php endwhile; ?>
      <!-- post navigation -->
    <?php else: ?>
      <!-- no posts found -->
    <?php endif; ?>
    <?php wp_reset_query(); ?>

Answer 1

I just needed to nominate the home page id the function:

<img src="<?php the_field('image_2', '245'); ?>" class="middle" alt="image2"/>