When you’re installing your AdSense code, one of the most important things to remember is that you can’t change the AdSense code in any way. You can’t add to it, take away from it, or otherwise change it. Period. It’s not only against the AdSense policies, but it could also render the code useless.
When Google generates code for you to use as a display on your site, there are some very important elements in that code. Among those elements is your user ID as well as information that tells Google what ads to display on your site.
If you start messing with the code, Google might not recognize it and ads won’t be pushed out to it. Or worse, ads that are completely irrelevant to your site might be pushed out. At least until Google figures out you monkeyed with the code — and then you could be banned from the AdSense program altogether.
So don’t ever mess with the AdSense code. Copy it; paste it; forget it.