query-post loop

Hello there!

I’ve got some problem with my query.

<?php $my_query = new WP_Query('posts_per_page='.$wm_post_number.'');
	while ($my_query->have_posts()) : $my_query->the_post();
	$do_not_duplicate = $post->ID; ?>

I’ve been building kind of administration panel to my theme, but this is not working good. I mean, this line” '.$wm_post_number.'
It’s variable which you can change by filling with your own value. But problem is, that when you change it, link like a “Previous posts” doesn’t work. By clicking there, on http://domain.com/page/2 you can see the same posts..

Have you got any idea to solve this problem?
Best regards!