I have the problem with Google Adsense API. I used Services Account to authen, and this is my code:
require_once dirname(__FILE__) . \'/google-api-php-client/Goo
Unfortunately at the moment AdSense API doesn't support Service Account, so AdSense data is invisible for API (that's why you getting that error).
Perhaps the best solution is to use "Web application" login: https://developers.google.com/adsense/management/getting_started#auth