Use of XXXcallbackhandler.java

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Hi all,
I have a question on the code generated by wsdl2java
There is a class named <service_name>CallbackHandler.java
And I used this callbackhandler in my asynchronous client code with
service.startAction(request, callbackhandler);
but the service is not called and callbackhandler is not invoked somehow.

Also, if I engage the addressing, the exception will be thrown
Unable to engage module : addressing

Does someone know an example to use callbackhandler?
or I have to use non blocking invocation?

I am using Axis2-1.4.1 and ran the client from Eclipse

my code looked like

SimpleServiceStub service = new SimpleServiceStub();
ConcatRequest request = new ConcatRequest();
ServiceClient client = service._getServiceClient();
Options options = client.getOptions();
options.setAction("urn:concat");

//Callback to handle the response
SimpleServiceCallbackHandler call = new SimpleServiceCallbackHandler(){
     public void receiveResultconcat(ConcatResponse result) {
         System.out.println(result.getConcatResponse());
     }
};

client.setOptions(options);
//Cause Unable to engage module : addressing
//client.engageModule("addressing");
request.setS1("123");
request.setS2("456");
service.startconcat(request, call);

Thank you in advance
David