Sort by exp date stopped working

I had a query to display a certain category of posts on a parent page, sorted by expiration date. It was working fine until I recently updated Post Expirator, then it stopped working.

The method I was using was the following:

$args = array(…’meta_key’ => ‘expiration-date’, ‘orderby’ => ‘meta_value’);

The query returned nothing unless I took those meta_key/orderby args out.

Please advise. Thanks.

http://wordpress.org/extend/plugins/post-expirator/