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The footer was where I had placed a couple of them when I was evaluating analytics sites. I had no issues.
But you know of course, javascript won't give an accurate data picture due to the number of people browsing with scripting disabled.
*edit*
Also hosts files block most of those sites.. You may want to check yours to be sure that isn't the trouble.
The more I know, the more I know that I really didn't wanna know.