does not recognize the images of nextgen gallery

hello,

I installed within the site:

the plugin Nextgen Gallery and Yoast WordPress SEO.

If within within an article (http://www.festeaziendaliaroma.com/fashion-bar-roma/)

you can see that I have added a gallery with nextgen gallery, but check to Yoast says: On this page there is no image, consider adding a few relevant.

but inside there is a gallery of nextgen gallery with several pictures.

how can I obtain recognition at Yoast, who in the article there are some photos?

http://wordpress.org/extend/plugins/wordpress-seo/