我第一次使用struts应用程序，在尝试运行这个程序时遇到了这个错误。它正在成功构建。
如何解决此错误？

com.opensymphony.xwork2.config.ConfigurationException: Unable to load configuration.

            at com.opensymphony.xwork2.config.ConfigurationManager.getConfiguration(ConfigurationManager.java:69)

            at org.apache.struts2.dispatcher.Dispatcher.getContainer(Dispatcher.java:959)

            at org.apache.struts2.dispatcher.Dispatcher.init_PreloadConfiguration(Dispatcher.java:463)

            at org.apache.struts2.dispatcher.Dispatcher.init(Dispatcher.java:496)

            at org.apache.struts2.dispatcher.InitOperations.initDispatcher(InitOperations.java:73)

            at org.apache.struts2.dispatcher.filter.StrutsPrepareAndExecuteFilter.init(StrutsPrepareAndExecuteFilter.java:61)

            at weblogic.servlet.internal.FilterManager$FilterInitAction.run(FilterManager.java:400)

            at weblogic.security.acl.internal.AuthenticatedSubject.doAs(AuthenticatedSubject.java:326)

            at weblogic.security.service.SecurityManager.runAsForUserCode(SecurityManager.java:196)

            at weblogic.servlet.provider.WlsSecurityProvider.runAsForUserCode(WlsSecurityProvider.java:203)

            at weblogic.servlet.provider.WlsSubjectHandle.run(WlsSubjectHandle.java:71)

            at weblogic.servlet.internal.FilterManager.initFilter(FilterManager.java:130)

            at weblogic.servlet.internal.FilterManager.loadFilter(FilterManager.java:92)

            at weblogic.servlet.internal.FilterManager.preloadFilters(FilterManager.java:72)

            at weblogic.servlet.internal.WebAppServletContext.preloadResources(WebAppServletContext.java:1917)

            at weblogic.servlet.internal.WebAppServletContext.start(WebAppServletContext.java:3063)

            at weblogic.servlet.internal.WebAppModule.startContexts(WebAppModule.java:1830)

            at weblogic.servlet.internal.WebAppModule.start(WebAppModule.java:875)

            at weblogic.application.internal.ExtensibleModuleWrapper$StartStateChange.next(ExtensibleModuleWrapper.java:360)

            at weblogic.application.internal.ExtensibleModuleWrapper$StartStateChange.next(ExtensibleModuleWrapper.java:356)

            at weblogic.application.utils.StateMachineDriver.nextState(StateMachineDriver.java:45)

            at weblogic.application.internal.ExtensibleModuleWrapper.start(ExtensibleModuleWrapper.java:138)

            at weblogic.application.internal.flow.ModuleListenerInvoker.start(ModuleListenerInvoker.java:124)

            at weblogic.application.internal.flow.ModuleStateDriver$3.next(ModuleStateDriver.java:237)

            at weblogic.application.internal.flow.ModuleStateDriver$3.next(ModuleStateDriver.java:232)

            at weblogic.application.utils.StateMachineDriver.nextState(StateMachineDriver.java:45)

            at weblogic.application.internal.flow.ModuleStateDriver.start(ModuleStateDriver.java:82)

            at weblogic.application.internal.flow.StartModulesFlow.activate(StartModulesFlow.java:52)

            at weblogic.application.internal.BaseDeployment$2.next(BaseDeployment.java:753)

            at weblogic.application.utils.StateMachineDriver.nextState(StateMachineDriver.java:45)

            at weblogic.application.internal.BaseDeployment.activate(BaseDeployment.java:263)

            at weblogic.application.internal.EarDeployment.activate(EarDeployment.java:67)

            at weblogic.application.internal.DeploymentStateChecker.activate(DeploymentStateChecker.java:165)

            at weblogic.deploy.internal.targetserver.AppContainerInvoker.activate(AppContainerInvoker.java:80)

            at weblogic.deploy.internal.targetserver.operations.AbstractOperation.activate(AbstractOperation.java:601)

            at weblogic.deploy.internal.targetserver.operations.ActivateOperation.activateDeployment(ActivateOperation.java:171)

            at weblogic.deploy.internal.targetserver.operations.ActivateOperation.doCommit(ActivateOperation.java:121)

            at weblogic.deploy.internal.targetserver.operations.StartOperation.doCommit(StartOperation.java:151)

            at weblogic.deploy.internal.targetserver.operations.AbstractOperation.commit(AbstractOperation.java:343)

            at weblogic.deploy.internal.targetserver.DeploymentManager.handleDeploymentCommit(DeploymentManager.java:895)

            at weblogic.deploy.internal.targetserver.DeploymentManager.activateDeploymentList(DeploymentManager.java:1422)

            at weblogic.deploy.internal.targetserver.DeploymentManager.handleCommit(DeploymentManager.java:454)

            at weblogic.deploy.internal.targetserver.DeploymentServiceDispatcher.commit(DeploymentServiceDispatcher.java:181)

            at weblogic.deploy.service.internal.targetserver.DeploymentReceiverCallbackDeliverer.doCommitCallback(DeploymentReceiverCallbackDeliverer.java:195)

            at weblogic.deploy.service.internal.targetserver.DeploymentReceiverCallbackDeliverer.access$100(DeploymentReceiverCallbackDeliverer.java:13)

            at weblogic.deploy.service.internal.targetserver.DeploymentReceiverCallbackDeliverer$2.run(DeploymentReceiverCallbackDeliverer.java:68)

            at weblogic.work.SelfTuningWorkManagerImpl$WorkAdapterImpl.run(SelfTuningWorkManagerImpl.java:643)

            at weblogic.invocation.ComponentInvocationContextManager._runAs(ComponentInvocationContextManager.java:348)

            at weblogic.invocation.ComponentInvocationContextManager.runAs(ComponentInvocationContextManager.java:333)

            at weblogic.work.LivePartitionUtility.doRunWorkUnderContext(LivePartitionUtility.java:54)

            at weblogic.work.PartitionUtility.runWorkUnderContext(PartitionUtility.java:41)

            at weblogic.work.SelfTuningWorkManagerImpl.runWorkUnderContext(SelfTuningWorkManagerImpl.java:617)

            at weblogic.work.ExecuteThread.execute(ExecuteThread.java:397)

            at weblogic.work.ExecuteThread.run(ExecuteThread.java:346)

Caused by: com.opensymphony.xwork2.config.ConfigurationException: Parent package is not defined: fw-default

            at com.opensymphony.xwork2.config.providers.XmlConfigurationProvider.buildPackageContext(XmlConfigurationProvider.java:689)

            at com.opensymphony.xwork2.config.providers.XmlConfigurationProvider.addPackage(XmlConfigurationProvider.java:539)

            at com.opensymphony.xwork2.config.providers.XmlConfigurationProvider.loadPackages(XmlConfigurationProvider.java:326)

            at org.apache.struts2.config.StrutsXmlConfigurationProvider.loadPackages(StrutsXmlConfigurationProvider.java:108)

            at com.opensymphony.xwork2.config.impl.DefaultConfiguration.reloadContainer(DefaultConfiguration.java:196)

            at com.opensymphony.xwork2.config.ConfigurationManager.getConfiguration(ConfigurationManager.java:66)

            ... 53 common frames omitted