什么时候会出现这样的错误?
<ERROR> <BeanSerializer> <serialize> <Exception:>
java.io.IOException: Non nillable element 'standardHeader' is null.
at org.apache.axis.encoding.ser.BeanSerializer.serialize(BeanSerializer.java:215)
at org.apache.axis.encoding.SerializationContext.serializeActual(SerializationContext.java:1426)
at org.apache.axis.encoding.SerializationContext.serialize(SerializationContext.java:914)
at org.apache.axis.message.RPCParam.serialize(RPCParam.java:200)
at org.apache.axis.message.RPCElement.outputImpl(RPCElement.java:433)
at org.apache.axis.message.MessageElement.output(MessageElement.java:1208)
at org.apache.axis.message.SOAPBody.outputImpl(SOAPBody.java:139)
at org.apache.axis.message.SOAPEnvelope.outputImpl(SOAPEnvelope.java:477)
at org.apache.axis.message.MessageElement.output(MessageElement.java:1208)
at org.apache.axis.SOAPPart.writeTo(SOAPPart.java:315)
at org.apache.axis.SOAPPart.writeTo(SOAPPart.java:269)
at org.apache.axis.SOAPPart.saveChanges(SOAPPart.java:530)
at org.apache.axis.attachments.AttachmentsImpl.getAttachmentCount(AttachmentsImpl.java:519)
at org.apache.axis.Message.getContentType(Message.java:475)
at org.apache.axis.transport.http.AxisServlet.doPost(AxisServlet.java:775)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:763)
at org.apache.axis.transport.http.AxisServletBase.service(AxisServletBase.java:327)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:856)
at weblogic.servlet.internal.StubSecurityHelper$ServletServiceAction.run(StubSecurityHelper.java:227)
at weblogic.servlet.internal.StubSecurityHelper.invokeServlet(StubSecurityHelper.java:125)
at weblogic.servlet.internal.ServletStubImpl.execute(ServletStubImpl.java:283)
at weblogic.servlet.internal.ServletStubImpl.execute(ServletStubImpl.java:175)
at weblogic.servlet.internal.WebAppServletContext$ServletInvocationAction.run(WebAppServletContext.java:3231)
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:2002)
at weblogic.servlet.internal.WebAppServletContext.execute(WebAppServletContext.java:1908)
at weblogic.servlet.internal.ServletRequestImpl.run(ServletRequestImpl.java:1362)
at weblogic.work.ExecuteRequestAdapter.execute(ExecuteRequestAdapter.java:21)
at weblogic.kernel.ExecuteThread.execute(ExecuteThread.java:145)
at weblogic.kernel.ExecuteThread.run(ExecuteThread.java:117)