Pagination don't works

I have this code:

Code

<br />
<?php<br />
$my_query = null;<br />
$paged = (get_query_var('paged')) ? get_query_var('paged') : 1;<br />
$my_query = new WP_Query(array('post_type'=>array('post','articulos'), 'posts_per_page' => 10, 'paged' => $paged));<br />
if ( $my_query->have_posts() ) : while ( $my_query->have_posts() ) : $my_query->the_post();<br />
if ($my_query->post->post_type == 'post') {?></p>
<p>div...</p>
<p><?php } if ($my_query->post->post_type == 'articulos') {?></p>
<p>div...</p>
<p><?php } else; endwhile;?><br />
<div id="navigation"><br />
<div class="previous"><?php previous_posts_link( __( 'Anterior' ) ); ?><div class="clear"></div></div><br />
<div class="next"><?php next_posts_link( __( 'Siguiente' ) ); ?><div class="clear"></div></div><br />
</div><br />
<?php endif; ?><br />
<div class="clear"></div><br />
</div>

But the pagination only works if more than 10 normal post.

[No bumping. If it’s that urgent, consider hiring someone.]