I have my query set up like this:
$article_query = new WP_Query(array( 'meta_key' => 'issue', 'meta_value' => $post->ID , 'post_type' => 'article', 'orderby' => 'order_number', 'order' => 'desc' ));
I want all the articles for an issue, sorted by the custom field 'order_number'
As it is, the order is ignored. I have read I need to set meta_key to 'order_number' to enable ordering by that key, but that filters by that key aswel, resulting in no results.
So, how to I sort by order_number?