【求助】java使用axis调用c#的webservice，传值始终为null

[aogusidulw]

        String url = "http://localhost:32828/WebServiceTest.asmx?" ;
		String namespace = "http://tempuri.org/"; 
		String methodName = "HelloWorld"; 
		String soapActionURI = "http://tempuri.org/HelloWorld";  
		Service service = new Service();
        
        Call call = (Call) service.createCall();

        call.setTargetEndpointAddress(new java.net.URL(url));  
        call.setUseSOAPAction(true);  
		
        call.setSOAPActionURI(soapActionURI);  
		
        call.setOperationName(new QName(namespace, methodName));  
        
         //call.addParameter("arg0", XMLType.XSD_STRING, ParameterMode.IN);改成arg0试过，不管用
        //call.addParameter(new QName("http://tempuri.org","name"), XMLType.XSD_STRING, ParameterMode.IN); 这样也试过还是不管用
        call.addParameter("name", XMLType.XSD_STRING, ParameterMode.IN);
        call.setReturnType(XMLType.XSD_STRING);
        
        Object[] params = new Object[] {"xxx"};
        
        String result = (String) call.invoke(params);

实在是搞不定了，照着网上的方法改了好几次，传过去的值总是null，求大神指教