No sample image to share on Facebook.

Good afternoon,
By sharing my page or an item of portfolio No image is displayed. It has the usual problem: Object at URL ‘http://garpopeluqueriasanxenxo.es/’ of type ‘website’ is invalid Because a required property ‘og: title’ of type ‘string’ was not provided.
I installed the Facebook plugin NextGEN but still gives the same problem. I also tried with SEO by Yoast, with Open Graph Facebook, Google+ and Twitter Card Tags …