Display most viewed post from last 30 days is not working correctly

I've try several different loop to display the most viewed post from the last 30 days . . However its just showing the post from 30 dasy ago . . not from the last 30 days . . not the most viewed . . iF anybody can help me out . .it will be fantastic, thank you =)

Here is my loop at the moment:

<ul>
<?php
function filter_where($where = '') {
    //posts in the last 30 days
    $where .= " AND post_date > '" . date('Y-m-d', strtotime('-30 days')) . "'";
    return $where;
}
add_filter('posts_where', 'filter_where');

query_posts('post_type=post&posts_per_page=3&orderby=post_views_count&order=ASC');

while (have_posts()): the_post(); ?>

<li><div class="tabber-image">

                        <a href="<?php the_permalink(); ?>" rel="bookmark" title="<?php the_title(); ?>"><?php the_post_thumbnail('small-thumb'); ?></a>

                    </div>

                    <div class="tabber-text">
                        <?php 
                        //$meta = get_post_meta(get_the_ID());
                        //$short_title = $meta['maxmag_featured_headline'][0];
                        ?>

                        <a href="<?php the_permalink() ?>" class="main-headline"><?php the_title(); ?></a></li>

<?php
endwhile;
wp_reset_query();
?>
</ul>

ANy help would be amazing . .thank you for your time