problem with xmlrpc

[guyhillyer]

Hi, I'm trying to use flickr-clojure with apache xmlrpc 3.1.1. When I invoke complete-authorization, I get the following exception:
org.apache.xmlrpc.common.XmlRpcExtensionException: Null values aren't supported, if isEnabledForExtensions() == false (NO_SOURCE_FILE:3)

I tried calling (. config setEnabledForExtensions true) in the defvar block for xml-rpc-client (line 37 in flickr_api.clj). Now when I try to complete-authorization, I get
org.apache.xmlrpc.client.XmlRpcHttpTransportException: HTTP server returned unexpected status: Internal Server Error.

I'm at a loss, being a complete novice with regard to clojure and apache xmlrpc. I wonder if you have an idea what the problem might be. Thanks.