Facebook Like Button

I'm having issues with the Facebook like button on my pages. On some pages (not all), I get a red 'Error' notice next to the like button. When clicking error it says that the "Page at ____ cannot be reached".

The URL Linter shows everything as fine with my pages.

Anything else I should check?

Using Javascript + X开发者_JAVA技巧FBML, no iframes.

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This error occurs if the page you're "Like"ing is not accessible from Facebook's servers. Are you testing this locally? Is it in a password-protected area? If either of these things are true, Facebook won't be able to find the page, and will assume that real users can't find it either.