I just ran your page through the Open Graph Error Checker (
developers.facebook.com/tools/debug). The first time, I got the error you mention above as well as another error about a timeout when trying to connect to your page.
The timeout error is why the first error was shown. Facebook wasn't able to scan your page at all, so it didn't see any tags.
I then re-ran the page through the debugger, and the second time it worked just fine. I'm not sure what happened that first time, but I can't see the problem anymore.
Can you try running it through the debugger to see if the error is still there? I'm assuming that's what you were doing in the first place, but if you were seeing the error somewhere else, just let me know.
Thanks,
Alex