Jon,
Not sure. That message usually means there's an error

It's not very obvious, but usually you can click the Error text and a popup will appear with the message. I personally just see a blank area with no Error text, so I can't click it... hopefully, you can. If there is a pretty message, let me know.
Beyond that, I've checked out everything on the page and it all seems right to me. Also, I tested in the
Like button dev page
and it works there. So, it seems something is causing problems on site. The only think I can think that may be conflicting is the Disqus plugin. Can you try, temporarily, disabling Disqus and see if that makes any difference?
Best of luck,
Alex