Can there be some sort of class loading problem? Here's something I read just now http://www.onjava.com/pub/a/onjava/2003/11/12/classloader.html In the case of a classloader problem maybe the ContextImpl class exists in different packages loaded by different classloaders? I need to find out why the wrong version of ContextImpl is loaded and how to get the correct one to be loaded. I saw in the debugger that the server was referring to the "jboss-ejb3-all.jar" file (provided by seam library) for the mx.util package. Maybe the MBean server tries to cast to this object but has another bytecode version? Any experts here in this field that are willing to sort this out? View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4035367#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...