Pellet has not been updated since Sep 16, 2010. Is not it developed anymore?
There will be a new release in the coming weeks, 2.2.3, which will probably be the last 2.x release. Most of the development efforts have been on Pellet 3, which should be released later this year. If you're curious about Pellet 3, there's a blog post detailing Pellet's new API, and there was a talk about it at Semtech this year.