[Plugin: Multiple Post Thumbnails] Upload secondary image just replace featured image

Hi,

I like the idea of this plugin but can´t make it work.
First of all I´m testing it on a WP multisite 3.2.1. And trying to use on a custom post type.

This is in functions.php

// Setp Secondary thumbnail + Plugin Multiple Post Thumbnails
$topstorythumb = new MultiPostThumbnails(array(
'label' => 'Secondary Image',
'id' => 'topstory',
'post_type' => 'magazin'
)
);
add_image_size('top-story', 300, 195, true);

and this on my index.php

<?php if (class_exists('MultiPostThumbnails')
						        && MultiPostThumbnails::has_post_thumbnail('magazin', 'topstory')) :
						        MultiPostThumbnails::the_post_thumbnail('magazin', 'topstory', NULL, 'top-story');
						        endif; ?>

With this the secondary image widget appears on the custom post type admin, but when I click to choose/upload an image and click to use it as a feature image just change the first(default feature image).
I thought was a problem of the WP multisite so I check to this topic and change the code of the plugin but the problem still.

Any idea?

Much thanx.

http://ww.wp.xz.cn/extend/plugins/multiple-post-thumbnails/