[Plugin: FeedWordPress] [Feedwordpress] Pinging won’t work

I run a site using feedwordpress at http://rsp-blogs.de, which works quite well.

But to reduce the amount of senseless traffic I generate by checking all feeds once an hour I would like to enable the “Pinging” feature.

With no success. I tried it with one of my own blogs, a wordpress 2.7.1 self-hosted install, entering http://rsp-blogs.de/xmlrpc.php in the “Update Services” field. It does not work.

I guess the URL is right, because if I enter that address in my Browser, I get “XML-RPC server accepts POST requests only.”

Yet Feedwordpress does not check the feed.

So my questions: Does it work for anybody?
Am I doing something wrong?