I was able to get this code to work using Eclipse with the following jars in my classpath: saxpath-1.0-FCS.jar, jaxen-1.0-FCS.jar and dom4j-1.6.jar.
I added all of these jars to my ear and deployed but failing with call to document.singleNode() method. I'm using JBoss 4.0.3SP1
I'm not getting any errors in log files or console, but the behavior is the same when I didn't have the correct dependencies in Eclipse. I have also tried copying the jars to the server\default\lib directory, but the same thing keeps happening.
It's probably a stupid oversight on my part, but I wanted to know if there was conflict some where I missed.