Extension is not functional in Chrome 18

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While the extension installs successfully from the Chrome Web Store and no errors or notifications are displayed when the extension is enable, the DNT header is never sent. Verified by visiting http://donottrack.us/ as well as examining the request headers via the developer tools.

Your browser does not support Do Not Track x
You have not enabled Do Not Track x

GET / HTTP/1.1
Host: donottrack.us
Connection: keep-alive
Cache-Control: max-age=0
User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/535.19 (KHTML, like Gecko) Chrome/18.0.1025.168 Safari/535.19
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8
Accept-Encoding: gzip,deflate,sdch
Accept-Language: en-US,en;q=0.8
Accept-Charset: ISO-8859-1,utf-8;q=0.7,*;q=0.3
If-None-Match: "f0ce1-1c37-4b10197c20080"-gzip
If-Modified-Since: Sat, 05 Nov 2011 19:11:46 GMT

Windows 7 x64
Chrome 18.0.1025.168 m