Hi Gavin, I am very sorry. You are right. It is not the @Transient problem. It is my composite primary key problem, which worked on EJB3 FD8 but failed on FD9. The problem is I only assigned values (groupId and memberId) to GroupMembershipPK class, but did not assigned group and member values to GroupMembership class. It seems FD9 has more restrict on it. Thank you very much and have a good holiday. View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=3988482#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...