It's a feed of my own. (You can check it here: http://sharewood.hu/index.rss, the feedburner version which has the pubsub links: http://feeds.feedburner.com/Sharewoodhu).
I've added superfeedr to the feed for a half day or so and the situation didn't change (superfeedr did show one subcriber to the feed which I assume was reader). I may try superfeedr for a longer period of time, but I feel like the issue is somewhere with reader because the pingshot service (which is just using pubsubhubbub.appspot.com) should work.
