Sort posts by "Popular" – What is wrong with this code?

I use this in my functions.php:

function wpb_set_post_views($postID) {
    $count_key = 'wpb_post_views_count';
    $count = get_post_meta($postID, $count_key, true);
    if($count==''){
        $count = 0;
        delete_post_meta($postID, $count_key);
        add_post_meta($postID, $count_key, '0');
    }else{
        $count++;
        update_post_meta($postID, $count_key, $count);
    }
}
//To keep the count accurate, lets get rid of prefetching
remove_action( 'wp_head', 'adjacent_posts_rel_link_wp_head', 10, 0);

function wpb_track_post_views ($post_id) {
    if ( !is_single() ) return;
    if ( empty ( $post_id) ) {
        global $post;
        $post_id = $post->ID;
    }
    wpb_set_post_views($post_id);
}
add_action( 'wp_head', 'wpb_track_post_views');

Then to retrieve the 6 most popular posts i use:

<?php
			$args = array(
				'posts_per_page' => 6,
				'meta_key' => 'wpb_post_views_count',
				'orderby' => 'meta_value_num',
				'order' => 'DESC'
			);
			$query = new WP_Query( $args );
			if ( $query->have_posts() ) : while ( $query->have_posts() ) : $query->the_post();
			?>

As you can see the function uses wpb_post_views_count, while you use _count-views_all, so it should work. However, you are using ‘showposts’ instead of ‘posts_per_page’. Maybe that is the problem?