Nothing displayed

Hello,

I’m just trying your plugin and have configured all needed parameters. Now, when I try to use it in the order admin panel, I’m getting redirected in a specific url (wp-admin/post.php?post=153642&action=edit&shippint_add_print=true&print_url=http%3A%2F%2Fwww.hdplace.fr%2Fwp-admin%2Fadmin-ajax.php%3Faction%3Dbulk_shipping_print%26ids%3D153642) but nothing happened
Normally, I have checked the “preview display” button, but nothing appears.
I have also verified that no error are reported in the browser console.

Is there something else to do?
Regards
Pat