>>>
Caused by: java.lang.RuntimeException: Unable to rollback transaction
at org.drools.persistence.jta.JtaTransactionManager.rollback(JtaTransactionManager.java:184)
at org.drools.persistence.SingleSessionCommandService.<init>(SingleSessionCommandService.java:131)
... 8 more
Caused by: java.lang.NullPointerException
at org.drools.persistence.jta.JtaTransactionManager.rollback(JtaTransactionManager.java:181)
... 9 more
<<<
My guess, is that you're trying to run it outside a J2EE container; it doesnt work. (see https://issues.jboss.org/browse/JBPM-3282)
Otherwise, double check the persistence.xml file