The URL Linter detects all of my og:image thumbnails, but Facebook only allows me to choose between 3 when I share the link (ref.). The site is W3C verified, and I've triple checked the meta tags I'm using. The images are square jpegs that are 300x300px.
Here's the link I'm trying to share, http://proactiveresources.com/021313. The website was created using Adobe Muse, and I'm testing the share on Google Chrome.
Does anyone have any further suggestions?