AxisFault: Problem with saving document

Hi,
When calling my web service, the client gets following exception. Please tell me the possible reasons for this exception. I don't have access to the client side code.

org.apache.axis2.AxisFault: Problem with saving document
at (AxisFault.java:430)
at (SAPMessageFormatter.java:83)
at (AxisRequestEntity.java:84)
at (EntityEnclosingMethod.java:499)
at (HttpMethodBase.java:2114)
at (HttpMethodBase.java:1096)
at (HttpMethodDirector.java:398)
at (HttpMethodDirector.java:171)
at (HttpClient.java:397)
at (HttpClient.java:346)
at (AbstractHTTPSender.java:542)
at (HTTPSender.java:189)
at (HTTPSender.java:75)
at ()
at ()
at (AxisEngine.java:448)
at InAClient.send(InA:401)
at InAClient.executeImpl(InA:228)
at Client.execute(Client.java:163)
at (SchemesServiceStubjava:2965)
at (HvsServiceImpljava:184)
at (Native Method)
at ()
at ()
at (Method.java:585)
at (AopUtils.java:301)
at ()
at ()
at ()
at ()
at (AspectJAfterAdvice.java:42)
at ()
at ()
at ()
at ()
at ()
at (JdkDynamicAopProxy.java:204)
at $Proxy35.validateHvsApplication(Unknown Source)
at (TestHvsServiceImpl.java:33)
at (Native Method)
at ()
at ()
at (Method.java:585)
at (TestMethodRunner.java:99)
at (TestMethodRunner.java:81)
at (BeforeAndAfterRunner.java:34)
at (TestMethodRunner.java:75)
at (TestMethodRunner.java:45)
at (TestClassMethodsRunner.java:66)
at (TestClassMethodsRunner.java:35)
at $1.runUnprotected(TestClassRunner.java:42)
at (BeforeAndAfterRunner.java:34)
at (TestClassRunner.java:52)
at (JUnit4TestReference.java:38)
at (TestExecution.java:38)
at (RemoteTestRunner.java:460)
at (RemoteTestRunner.java:673)
at (RemoteTestRunner.java:386)
at (RemoteTestRunner.java:196)
Caused by: Problem with saving document
at $33.serialize(SchemesServiceStub.java:4888)
at (MSourcedElementImpl.java:664)
at MElementImpl.internalSerialize(MElementImpl.java:9 18)
at (MElementImpl.java:947)
at (SAPEnvelopeImpl.java:240)
at (SAPEnvelopeImpl.java:228)
at (MElementImpl.java:947)
at MNodeImpl.serializeAndConsume(MNodeImpljava:471)
at (SAPMessageFormatter.java:79)
57 more