jbpm - Service Task Exception

public class ProcessMain {

public static void main(String[] args) {
    KieServices ks = KieServices.Factory.get();
    KieContainer kContainer = ks.getKieClasspathContainer();
    KieBase kbase = kContainer.getKieBase("kbase");
    RuntimeManager manager = createRuntimeManager(kbase);
    RuntimeEngine engine = manager.getRuntimeEngine(null);
    KieSession ksession = engine.getKieSession();

    ksession.getWorkItemManager().registerWorkItemHandler("Service Task", new ServiceTaskHandler());
    InputData InputData = new InputData("123","23");
    Map<String, Object> param  = new HashMap<String, Object>();
    param.put("in", InputData);

    ksession.startProcess("com.sample.bpmn.hello2",param);

// ksession.startProcess("com.sample.test"); manager.disposeRuntimeEngine(engine);

    System.exit(0);
}

private static RuntimeManager createRuntimeManager(KieBase kbase) {
    JBPMHelper.startH2Server();
    JBPMHelper.setupDataSource();
    EntityManagerFactory emf = Persistence.createEntityManagerFactory("org.jbpm.persistence.jpa");
    RuntimeEnvironmentBuilder builder = RuntimeEnvironmentBuilder.Factory.get()
        .newDefaultBuilder().entityManagerFactory(emf)
        .knowledgeBase(kbase);
    return RuntimeManagerFactory.Factory.get()
        .newSingletonRuntimeManager(builder.get(), "com.sample:example:1.0");
}

}

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Exception in thread "main" java.lang.RuntimeException: Error while creating KieBase[Message [id=1, kieBase=kbase, level=ERROR, path=sample2.bpmn, line=-1, column=0 text=unable to parse xml : Exception class java.lang.NullPointerException : null]]

when I created on service in the BPMN , it worked fine. but when I created one more service tasks, will met Null point error. seem it is the parse xml exception.I cant locate the exception .Thanks.