What’s wrong with this query?

I found this code for query posts from many cats, but some how it’s only display 5posts. I have changed to 10 but still only 5posts..

Can any1 tell me how to query to get posts from cat 2,3,4,5,6 ect

NOT WORKING CODE HERE:

<?php
$posts = query_posts('cat=3,4,5,6,7,8&numberposts=6');
foreach ($posts as $post) :
?>
<div class="Box"><a href="<?php the_permalink(); ?>" title="<?php the_title() ?>"><?php the_title() ?></a><small><?php the_time('F jS, Y') ?></small></div>
<?php
endforeach;
?>