The issue is the ClassCastException logged at DEBUG. (Tangent -- I'd thought in 2.0 we were going to fail start if this kind of thing occurred; seems we didn't.) I can reproduce this on an AS 4.2.x build. Works fine on an trunk (AS 5) build. Only thing I can think of is an incompatibility in the javax.transaction.TransactionManager class between the two (AS 5 is JEE 5 based; 4.x is J2EE 1.4). That doesn't really jive with my understanding of how dynamic binding in Java works, though. All I can suggest as a shot in the dark is to check out the source for JBC 2.0.0.GA, replace the jboss-j2ee.jar in the lib dir with the one from your JBoss AS' server/all/lib dir, rebuild JBC and see if that solves the problem. View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4079684#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...