Ruby Scripts

I can't post an annotation on the w3c server with the script annpost.rb :
http://www.w3.org/2001/sw/Europe/200209/annodemo/annopost.rb

I have this error : 
/usr/lib/ruby/1.6/net/protocol.rb:221:in `error!': 401 Unauthorized (Net::ProtoFatalError)
        from /usr/lib/ruby/1.6/net/http.rb:708:in `value'
        from /usr/lib/ruby/1.6/net/http.rb:402:in `post'
        from annopost.rb:104

I need help, thank you.