Estou com problema no netbeans, não consigo carregar dados na combobox

Front-end
#1

Por favor ajuda - me estou com este problema já há uma semana.

Aqui está o erro que ele envia…

HTTP Status 500 -

type Exception report

message

descriptionThe server encountered an internal error () that prevented it from fulfilling this request.

exception

javax.servlet.ServletException: #{RegistosMB.salvarRegistos}: javax.ejb.EJBException: Transaction aborted; nested exception is: javax.transaction.RollbackException: Transaction marked for rollback.

root cause

javax.faces.FacesException: #{RegistosMB.salvarRegistos}: javax.ejb.EJBException: Transaction aborted; nested exception is: javax.transaction.RollbackException: Transaction marked for rollback.

root cause

javax.faces.el.EvaluationException: javax.ejb.EJBException: Transaction aborted; nested exception is: javax.transaction.RollbackException: Transaction marked for rollback.

root cause

javax.ejb.EJBException: Transaction aborted; nested exception is: javax.transaction.RollbackException: Transaction marked for rollback.

note The full stack traces of the exception and its root causes are available in the Sun GlassFish Enterprise Server v2.1 logs.
Sun GlassFish Enterprise Server v2.

#2