Getting "required property 'og:image:url' of type 'url' was not provided." error on Facebook Debugger

I'm trying to see why when I share a post on Facebook I don't get see all the images on the specific page. So I'm using the Facebook Debugger page to see where the problem might be and it says that "Object at URL 'http://www.myurl' of type 'article' is invalid because a required property 'og:image:url' of type 'url' was not provided."

But in Metatag under Image URL I've added "[node:field_image]" because my photos are using this field.

Why am I getting this error? I can see only the first image when I do a facebook share but not the other images.

Thank you for your help.