Q:

How come adding this to the doctype messes up my meta tags?

When I ran my website through facebook lint (http://developers.facebook.com/tools/debug) ...everything was fine.
This was my doctype before:
<!DOCTYPE html>

Then, I added the "xmlns" to my doctype.
<!DOCTYPE html  xmlns="http://www.w3.org/1999/xhtml" xmlns:fb="http://www.facebook.com/2008/fbml">

I ran it through Facebook Lint again...and facebook could not scan any of my meta tags anymore. Why? It said all the properties are missing.

A:

The xmlns properties go onto the <html> tag, not the doctype.

