Silly me, I know what happened. I have the recipe customized to fetch news only a week old, and fro some reason the new yorker has bi-weekly editions on august. There was just nothing to fetch this week.
I have noticed two things, though, with this recipe that you might want to improve for future versions. One is that, compared to other recipes, this one does not group articles by section, there are all scrambled together. Then again that might just be due to the source feed itself.
The other is a weird thing: in my Kindle 2, I am allowed to keep old editions of all my subscriptions, including those dowloaded through Calibre, with the exception of the New Yorker. The option to keep the old edition is missing.
Thanks a lot for your help and keep the great work.