Hi,
You might want to check my post here, I had something related :--
http://community.jboss.org/thread/170488?tstart=0
Since you're using JBoss server, that should be easier. You might want to quote your persistence.xml and the way you're initializing the StatefulKnowledgeSession.
eg.
Mare Geldenhuys post on:
// Change second parameter to where you get your transaction manager from
env.set( EnvironmentName.TRANSACTION_MANAGER, TransactionManagerServices.getTransactionManager() );
Good luck,