From the article on the plugin site (http://ppfeufer.de/wordpress-plugin/feed-stats-for-wordpress-reworked-for-php-5-3/) it mentions that Awareness API needs to be manually activated from within the feedburner account.
This is not mentioned in the instructions.
What else is missing? I' saw something about cache in the comments too.
Can ALL required steps be included in the instructions? Otherwise you're better off having no instructions at all, and let people work it out without being mislead.