Module only works with /?google_debug

The module wasn't delivering any ads, so I went to the Google Ad Manager site and found that they have a debug switch, which is example.com/?google_debug.

With that switch turned on. The ads are delivered.

I created the mytheme_preprocess_page(&$vars) function in template.tpl.php, and set up everything else per the instructions. I diff'ed the page source with debug on and debug off (that is, with the parameter and without it.) The difference is that with debug off, this code doesn't get generated:

<script type="text/javascript">
  GA_googleAddSlot("ca-pub-0000000000000000", "VS-default-rightsidebar-120x600");
</script>
<script type="text/javascript">
  GA_googleFetchAds();
</script>

Interestingly, if, as a test, I hard-code the above into my page.tpl.php, it gets stripped out!