Error 500--Internal Server Error

org.jasig.cas.client.validation.TicketValidationException: 
		未能够识别出目标 'ST_portal.dlut.edu.cn_-4362556-iD0N97n24U5HwbeeNRYw'票根
	
	at org.jasig.cas.client.validation.Cas20ServiceTicketValidator.parseResponseFromServer(Cas20ServiceTicketValidator.java:86)
	at org.jasig.cas.client.validation.AbstractUrlBasedTicketValidator.validate(AbstractUrlBasedTicketValidator.java:217)
	at org.jasig.cas.client.validation.AbstractTicketValidationFilter.doFilter(AbstractTicketValidationFilter.java:169)
	at weblogic.servlet.internal.FilterChainImpl.doFilter(FilterChainImpl.java:82)
	at com.neusoft.cas.AuthenticationFilter.doFilter(AuthenticationFilter.java:142)
	at weblogic.servlet.internal.FilterChainImpl.doFilter(FilterChainImpl.java:82)
	at org.jasig.cas.client.session.SingleSignOutFilter.doFilter(SingleSignOutFilter.java:76)
	at weblogic.servlet.internal.FilterChainImpl.doFilter(FilterChainImpl.java:82)
	at com.sg.security.XSSSecurityFilter.doFilter(XSSSecurityFilter.java:71)
	at weblogic.servlet.internal.FilterChainImpl.doFilter(FilterChainImpl.java:82)
	at weblogic.servlet.internal.WebAppServletContext$ServletInvocationAction.wrapRun(WebAppServletContext.java:3869)
	at weblogic.servlet.internal.WebAppServletContext$ServletInvocationAction.run(WebAppServletContext.java:3832)
	at weblogic.security.acl.internal.AuthenticatedSubject.doAs(AuthenticatedSubject.java:344)
	at weblogic.security.service.SecurityManager.runAsForUserCode(SecurityManager.java:197)
	at weblogic.servlet.provider.WlsSecurityProvider.runAsForUserCode(WlsSecurityProvider.java:203)
	at weblogic.servlet.provider.WlsSubjectHandle.run(WlsSubjectHandle.java:71)
	at weblogic.servlet.internal.WebAppServletContext.processSecuredExecute(WebAppServletContext.java:2505)
	at weblogic.servlet.internal.WebAppServletContext.doSecuredExecute(WebAppServletContext.java:2354)
	at weblogic.servlet.internal.WebAppServletContext.securedExecute(WebAppServletContext.java:2329)
	at weblogic.servlet.internal.WebAppServletContext.execute(WebAppServletContext.java:2307)
	at weblogic.servlet.internal.ServletRequestImpl.runInternal(ServletRequestImpl.java:1798)
	at weblogic.servlet.internal.ServletRequestImpl.run(ServletRequestImpl.java:1752)
	at weblogic.servlet.provider.ContainerSupportProviderImpl$WlsRequestExecutor.run(ContainerSupportProviderImpl.java:272)
	at weblogic.invocation.ComponentInvocationContextManager._runAs(ComponentInvocationContextManager.java:352)
	at weblogic.invocation.ComponentInvocationContextManager.runAs(ComponentInvocationContextManager.java:337)
	at weblogic.work.LivePartitionUtility.doRunWorkUnderContext(LivePartitionUtility.java:57)
	at weblogic.work.PartitionUtility.runWorkUnderContext(PartitionUtility.java:41)
	at weblogic.work.SelfTuningWorkManagerImpl.runWorkUnderContext(SelfTuningWorkManagerImpl.java:651)
	at weblogic.work.ExecuteThread.execute(ExecuteThread.java:420)
	at weblogic.work.ExecuteThread.run(ExecuteThread.java:360)