Hi Luca,
Have you tried flushing the rewrite rules by visiting Settings > Permalinks? The feed is working fine for me. You may wish to try disabling other plug-ins first (and switching to TwentyTwelve) to see if there's a plug-in conflict.
Might I suggest using the plug-in forums to get help resolving issues? The star rating and review is intended as a review of the plug-in rather than a method to announce you're experiencing some particular problem. It comes across as quite rude.
All the best,
Stephen