category__and example

I am having trouble using the category__and parameter within query_posts() and am looking for some help with my code. The template I’m editing is category.php (based on archive.php). Here is what I have so far.

<?php

	get_header();

	query_posts(array('showposts' => 1, 'category__and' => array(2,6)));

	if (have_posts()) : ?>

		  <?php $post = $posts[0]; // Hack. Set $post so that the_date() works. ?>
		  <?php /* If this is a category archive */ if (is_category()) { ?>
		<h2 class="pagetitle">Archive for the ‘<?php single_cat_title(); ?>’ Category</h2>
		  <?php } ?>
		<?php while (have_posts()) : the_post(); ?>
			<div <?php post_class() ?>>
				<h3 id="post-<?php the_ID(); ?>"><a href="<?php the_permalink() ?>""><?php the_title(); ?></a></h3>
				<?php the_content() ?>
			</div>
		<?php endwhile; ?>
	<?php else :
		printf("<h2 class='center'>Sorry, but there aren't any posts in the %s category yet.</h2>", single_cat_title('',false));
		get_search_form();
	endif;

	get_sidebar();
	get_footer(); 

?>

Instead of seeing the one post that is part of both category 2 and 6, I see “Sorry, but there aren’t any posts in the category yet.”