Related post by category in all post type

Hi everyones,

I want to create a related post by category but related in all post type. I have 2 post-types, the first (default post type) for artist that I manage, and a second for news/press release.

So I want to show related post by categories on single of default post type, but this related need to show post from second post type.

I tried this, but it doesn’t work with all post-type.
Any idea ?

<?php

$related = get_posts( array( 'category__in' => wp_get_post_categories($post->ID), 'numberposts' => 5, 'post__not_in' => array($post->ID) ) );
if( $related ) foreach( $related as $post ) {
setup_postdata($post); ?>
 <ul>
        <li>
        <a href="<?php the_permalink() ?>" rel="bookmark" title="<?php the_title(); ?>"><?php the_title(); ?></a>
            <?php the_content('Read the rest of this entry &raquo;'); ?>
        </li>
    </ul>
<?php }
wp_reset_postdata(); ?>

Thanks for your help, have a nice sunday !