Struts2 weblogic 11g上的Jasperreport空指针

我已经部署了使用jasperreports插件的struts2应用程序。部署时 在Glassfish3和Tomcat中，报告工作正常。但当我部署到Weblogic 11g时 给出了以下NPE

java.lang.NullPointerException
    at weblogic.servlet.internal.ServletResponseImpl.sendError(ServletResponseImpl.java:645)
    at org.apache.struts2.dispatcher.Dispatcher.sendError(Dispatcher.java:819)
    at org.apache.struts2.dispatcher.Dispatcher.serviceAction(Dispatcher.java:519)
    at org.apache.struts2.dispatcher.ng.ExecuteOperations.executeAction(ExecuteOperations.java:77)
    at org.apache.struts2.dispatcher.ng.filter.StrutsPrepareAndExecuteFilter.doFilter(StrutsPrepareAndExecuteFilter.java:91)
    at weblogic.servlet.internal.FilterChainImpl.doFilter(FilterChainImpl.java:56)
    at org.springframework.orm.hibernate3.support.OpenSessionInViewFilter.doFilterInternal(OpenSessionInViewFilter.java:198)
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:76)
    at weblogic.servlet.internal.FilterChainImpl.doFilter(FilterChainImpl.java:56)
    at weblogic.servlet.internal.WebAppServletContext$ServletInvocationAction.run(WebAppServletContext.java:3592)
    at weblogic.security.acl.internal.AuthenticatedSubject.doAs(AuthenticatedSubject.java:321)
    at weblogic.security.service.SecurityManager.runAs(SecurityManager.java:121)
    at weblogic.servlet.internal.WebAppServletContext.securedExecute(WebAppServletContext.java:2202)
    at weblogic.servlet.internal.WebAppServletContext.execute(WebAppServletContext.java:2108)
    at weblogic.servlet.internal.ServletRequestImpl.run(ServletRequestImpl.java:1432)
    at weblogic.work.ExecuteThread.execute(ExecuteThread.java:201)
    at weblogic.work.ExecuteThread.run(ExecuteThread.java:173)

有人知道如何解决这个问题吗？ 我正在使用struts2.2.3和struts2 jasper reports插件2.2.3