Only return posts from last 30 days.

Hi,

I hope someone might be able to help me.

I am on 2.9.2 and thematic child theme

I am trying to filter the main loop, and category loop and search results to only return posts from the last 30 days.

I think I am close to solving the main loop and category loop issue but it is not working

I have the following code in my functions.php

// Filter Index Loop
function remove_thematic_index_loop() {
      remove_action ('thematic_indexloop','thematic_index_loop');
}
add_action('init','remove_thematic_index_loop');

function my_index_loop() {

//based on Austin Matzko's code from wp-hackers email list
function filter_where($where = '') {
//posts in the last 30 days
$where .= " AND post_date > '" . date('Y-m-d', strtotime('-30 days')) . "'";
return $where;
}
add_filter('posts_where', 'filter_where');
query_posts($query_string);

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

          <div id="post-<?php the_ID(); ?>" class="<?php thematic_post_class(); ?>">
              <?php thematic_postheader(); ?>
              <div class="entry-content">
<?php thematic_content(); ?>
				</div>
              <?php thematic_postfooter(); ?>
          </div><!-- .post -->

      <?php endwhile;
}
add_action('thematic_indexloop', 'my_index_loop');

Does anyone know where I am going wrong here? I tried replacing Austins filter with query_posts('posts_per_page=2'); and this worked.

Thanks

BAC