Google Analytics GIF request not sent

I'm having some troubles setting up Google Analytics. I downloaded the Google Analytics Debugging extension for Chrome and if I take a look at the console, the __utm.gif request is never sent. I triple-checked my code, and everything is fine. The debugging version of ga.js is downloaded properly. In fact, I have the exact same problem as this guy that never got an answer...

For the sake of it, here is my tracking code (with UA-########-# properly replaced in my original code, of course)

var _gaq = _gaq || [];
_gaq.push(['_setAccount', 'UA-########-#']);
_gaq.push(['_trackPageview']);

(function() {
    var ga = document.createElement('script'); ga.type = 'text/javascript'; ga.async = true;
    ga.src = ('https:' == document.location.protocol ? 'https://ssl' : 'http://www') + '.google-analytics.com/ga.js';
    var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(ga, s);
})();

Everything is set up properly, and here is what I get in the console output :

_gaq.push processing : "[_setAccount, UA-########-#]"
_gaq.push processing : "[_trackPageview]"
Track Pageview

And then nothing else. I tried with a colleague's personal website that I know has Google Analytics installed and I can see the request for the .gif file.

Anyone ever had this problem ?