the_date() not working

I tried to add a line of code to my theme in order to show the post author and date/time of the post. This line of code only works on some of the posts. Other posts simply return blanks.

<div class="postmeta">Posted by <?php the_author_posts_link(); ?> on <?php the_date('F j, Y \a\t g:i a'); ?>.</div>

Any ideas why? http://charlieholder.com/blog/ to view live.