exporting a topic to google reader results in error

exporting my topic to google reader results in error: "The feed being requested cannot be found."

I created a single topic, hovered over the rss icon which showed a number of readers to export to, I chose the first, google reader, which in turn gave me the above error msg.

I then tried exporting the topic feed to an OPML file which I successfully imported in to gr, but when I clicked on the feed in gr to read it, I got the same 'feed not found' error.

thanks for your help,
Alain.