I'm having a problem similar to the one you had a year ago. I'm with JBoss 4.0.3 and having some CMP 2.0 deployed and when inserting I get the javax.ejb.CreateException: Primary key for created instance is null error.
On creation I always pass a null value as I did put the oracle sequence in my jbosscmp-jdbc.xml file for my entity. This is happening since I put INSERT-AFTER-EJB-POST-CREATE to true in the standardjboss.xml
Did you solve the issue ??
Thanks a lot,