How to order posts by custom field in a specific category

Hi everyone!
I know, there are dozens of posts with similar problems and I’ve tried all the possibile solutions (probably just missing the right one.. haha)

Like the title, i want to order the posts in a specific category by a custom field created by Types plugin and called “position” (it’s a numeric value, like “20150220”)

Now, in the “category.php” page I’ve try this code:

if(is_category('77')){
	query_posts('cat=77&meta_key=position&orderby=meta_value&order=ASC');}

and then the page continues with:

<?php if ( have_posts() ) : ?>
	<?php while ( have_posts() ) : the_post(); ?>
		<?php
		/* Get the content template */
		get_template_part( 'content', get_post_format() );
		?>
	<?php endwhile; ?>
<?php else : ?>
	<?php
	/* Get the none-content template (error) */
	get_template_part( 'content', 'none' );
	?>
<?php endif; ?>

But the result is: “No articles found”