put query_posts of 1 category in 3 horizontal columns

hi, im trying to put inside 3 columns query_posts of 1 category

<div id="content">
<?php $count = 1;
$col_count = 3;
$num_of_posts = $wp_query->post_count;
$post_per_column = ceil($num_of_posts / $col_count); ?>
<div id="col1">
<?php query_posts($query_string . '&cat=28'); ?>
 <?php if ( have_posts() ) : while ( have_posts() ) : the_post(); ?>
                                <div class="item entry" id="post-<?php the_ID(); ?>"></div>
<?php global $post; ?>
<div class="post" style="background: url(<?php echo $src[0]; ?>) #fff no-repeat;">
<div class="post_title"><h2><a href="<?php the_permalink(); ?>"><?php the_title(); ?></a></h2></div>
</div>
 <?php if($count == $post_per_column) { echo '</div><div id="col2">'; }
  if($count == 2*$post_per_column) { echo '</div><div id="col3">'; }
  $count++;
  endwhile;
?>
<?php endif; ?>

<br class="clearBoth"/>

i founded on the web this code and i modified for my web site but i have some issue i have the 3 columns white background but the post go only on the first columns

any help ?! thanks!