Conditional Tags and WP_Query – WordPress Buggy ?

I’m trying to show latest post from a category


<?php $my_query = new WP_Query('showposts=15&cat=6'); while ($my_query->have_posts()) : $my_query->the_post(); $do_not_duplicate = $post->ID; ?>
SOME CODE
<?php endwhile; ?>

and to show after this a simple box inside a statement

<?php if (is_home() && !is_paged()) {?><?php include (TEMPLATEPATH . '/box.php'); ?><?php } ?>

Conditional Tag is not respected from WordPress showing the box in every page. WordPress must show the box only on home page (index.php).

Do you have solutions ?

Best Regards