"venuwin" wrote : The client is a plain java class. So this statement anonymous wrote : I am running the client on Jboss 5. is incorrect :) Your client is not on JBoss5. The client classpath should always have the same jboss jar files that are on the server side. So if you are doing a lookup from a standalone client against JBoss-4.x, then on the client classpath, you should have the jar files present in %JBOSS_HOME%/client folder of the JBoss-4.x server. And if you are doing a lookup from a standalone client against JBoss-5, then you should have the jars from JBoss-5 client folder. View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4203893#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...