Unable to instantiate default tuplizer

Ola pessoal estou precisando da ajuda de voces. estou tendo o seguinte erro quando tento rodar minha aplicacao

e nao entendo qual o motivo, acredito que seja um erro por conta do mapeamento.

a utilizei o software chamado visual paradigma para gerar os beans e mapaementos
e tambem estou utilizando o framework mentawai, e minha aplicacao esta rodando com o jetty

espero que voce possam me ajudar. de ja agradeço…

org.hibernate.HibernateException: Unable to instantiate default tuplizer [org.hibernate.tuple.entity.PojoEntityTuplizer]
	at org.hibernate.tuple.entity.EntityTuplizerFactory.constructTuplizer(EntityTuplizerFactory.java:110)
	at org.hibernate.tuple.entity.EntityTuplizerFactory.constructDefaultTuplizer(EntityTuplizerFactory.java:135)
	at org.hibernate.tuple.entity.EntityEntityModeToTuplizerMapping.<init>(EntityEntityModeToTuplizerMapping.java:80)
	at org.hibernate.tuple.entity.EntityMetamodel.<init>(EntityMetamodel.java:323)
	at org.hibernate.persister.entity.AbstractEntityPersister.<init>(AbstractEntityPersister.java:456)
	at org.hibernate.persister.entity.SingleTableEntityPersister.<init>(SingleTableEntityPersister.java:131)
	at org.hibernate.persister.PersisterFactory.createClassPersister(PersisterFactory.java:84)
	at org.hibernate.impl.SessionFactoryImpl.<init>(SessionFactoryImpl.java:267)
	at org.hibernate.cfg.Configuration.buildSessionFactory(Configuration.java:1341)
	at org.mentawai.filter.HibernateFilter.init(HibernateFilter.java:152)
	at org.mentawai.filter.HibernateFilter.<init>(HibernateFilter.java:112)
	at br.com.linkzsistemas.framework.core.LinkzApplicationManager.loadActions(LinkzApplicationManager.java:213)
	at TrainningApplicationManager.loadActions(TrainningApplicationManager.java:198)
	at org.mentawai.core.MultiApplicationManager.loadActions(MultiApplicationManager.java:105)
	at org.mentawai.core.Controller.initApplicationManager(Controller.java:349)
	at org.mentawai.core.Controller.init(Controller.java:207)
	at org.eclipse.jetty.servlet.ServletHolder.initServlet(ServletHolder.java:421)
	at org.eclipse.jetty.servlet.ServletHolder.doStart(ServletHolder.java:245)
	at org.eclipse.jetty.util.component.AbstractLifeCycle.start(AbstractLifeCycle.java:55)
	at org.eclipse.jetty.servlet.ServletHandler.initialize(ServletHandler.java:691)
	at org.eclipse.jetty.servlet.ServletContextHandler.startContext(ServletContextHandler.java:192)
	at org.eclipse.jetty.webapp.WebAppContext.startContext(WebAppContext.java:995)
	at org.eclipse.jetty.server.handler.ContextHandler.doStart(ContextHandler.java:579)
	at org.eclipse.jetty.webapp.WebAppContext.doStart(WebAppContext.java:381)
	at org.mortbay.jetty.plugin.JettyWebAppContext.doStart(JettyWebAppContext.java:114)
	at org.eclipse.jetty.util.component.AbstractLifeCycle.start(AbstractLifeCycle.java:55)
	at org.eclipse.jetty.server.handler.HandlerCollection.doStart(HandlerCollection.java:165)
	at org.eclipse.jetty.server.handler.ContextHandlerCollection.doStart(ContextHandlerCollection.java:162)
	at org.eclipse.jetty.util.component.AbstractLifeCycle.start(AbstractLifeCycle.java:55)
	at org.eclipse.jetty.server.handler.HandlerCollection.doStart(HandlerCollection.java:165)
	at org.eclipse.jetty.util.component.AbstractLifeCycle.start(AbstractLifeCycle.java:55)
	at org.eclipse.jetty.server.handler.HandlerWrapper.doStart(HandlerWrapper.java:92)
	at org.eclipse.jetty.server.Server.doStart(Server.java:226)
	at org.mortbay.jetty.plugin.JettyServer.doStart(JettyServer.java:69)
	at org.eclipse.jetty.util.component.AbstractLifeCycle.start(AbstractLifeCycle.java:55)
	at org.mortbay.jetty.plugin.AbstractJettyMojo.startJetty(AbstractJettyMojo.java:433)
	at org.mortbay.jetty.plugin.AbstractJettyMojo.execute(AbstractJettyMojo.java:377)
	at org.mortbay.jetty.plugin.JettyRunMojo.execute(JettyRunMojo.java:577)
	at org.apache.maven.plugin.DefaultBuildPluginManager.executeMojo(DefaultBuildPluginManager.java:105)
	at org.apache.maven.lifecycle.DefaultLifecycleExecutor.execute(DefaultLifecycleExecutor.java:577)
	at org.apache.maven.lifecycle.DefaultLifecycleExecutor.execute(DefaultLifecycleExecutor.java:324)
	at org.apache.maven.DefaultMaven.doExecute(DefaultMaven.java:247)
	at org.apache.maven.DefaultMaven.execute(DefaultMaven.java:104)
	at org.apache.maven.cli.MavenCli.execute(MavenCli.java:427)
	at org.apache.maven.cli.MavenCli.doMain(MavenCli.java:157)
	at org.apache.maven.cli.MavenCli.main(MavenCli.java:121)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:613)
	at org.codehaus.plexus.classworlds.launcher.Launcher.launchEnhanced(Launcher.java:290)
	at org.codehaus.plexus.classworlds.launcher.Launcher.launch(Launcher.java:230)
	at org.codehaus.plexus.classworlds.launcher.Launcher.mainWithExitCode(Launcher.java:409)
	at org.codehaus.plexus.classworlds.launcher.Launcher.main(Launcher.java:352)

Será que não esqueceu de adicionar algum jar?
Att.