[Plugin: Microdata for SEO by Optimum7.com] How to edit a previous entry?

Hello,
I can’t reedit a previous entry within the editor. I’ve selected the shortcode and then clicked on the icon; nothing’s happened.

Am I missing something?

Another question : could I add schema.org types adding classes in the types.php file?

Thx a lot for your reply.

http://wordpress.org/extend/plugins/microdata-for-seo-by-optimum7com/