Error message when creating sales order

I am testing  ofbiz 7.12 on a derby database.
I entered through ecomseo an order. When checking out a creating the order I get the following error message:



The Following Errors Occurred:

Problems reading the database, please try again.ERROR: Could not create order (problem invoking the service: org.apache.ofbiz.entity.transaction.GenericTransactionException: The current transaction is marked for rollback, not beginning a new transaction and aborting current operation; the rollbackOnly was caused by: rollback called in Entity Engine SQLProcessorjava.lang.Exception: Current Location Stack (Current Location Stack) (The current transaction is marked for rollback, not beginning a new transaction and aborting current operation; the rollbackOnly was caused by: rollback called in Entity Engine SQLProcessorjava.lang.Exception: Current Location Stack (Current Location Stack)))

Is this a bug?