AJAX Comment Reply issues

I’m currently building a new theme for my blog, though I’m facing an issue with AJAX comment reply.

This is in my header:

<?php if ( is_singular() ) wp_enqueue_script( 'comment-reply' ); ?>

Checking my source when the page loads, comment-reply.js properly loads.

However, when I click Reply, the page still reloads, this time with “?replytocom=89374#respond” attached to the end of the URL.

My current theme supports the AJAX commenting just fine, so it’s not an issue with plugins. It has to be an issue with the new theme I’m currently creating. Though I’ve reviewed it many times, and it all seems well in order. Even in the comment template, I’ve included:

<li <?php comment_class(); ?> id="li-comment-<?php comment_ID( ); ?>">

          <div id="comment-<?php comment_ID() ?>">

Any ideas as to what I could be doing wrong?