WebService SAAJ 未将对象引用设置到对象的实例.急 , 在线等...

代码如下:public static SOAPMessage getSupportCity(String arg) throws IOException{  
       MessageFactory fac=null;  
       SOAPMessage reqMsg=null;  
       try {  
            fac=MessageFactory.newInstance(SOAPConstants.SOAP_1_1_PROTOCOL);  
            reqMsg=fac.createMessage();  //SOAPMessage
               
            reqMsg.setProperty(SOAPMessage.CHARACTER_SET_ENCODING, "UTF-8");  
            reqMsg.setProperty(SOAPMessage.WRITE_XML_DECLARATION, "true");  
              
            SOAPEnvelope env=reqMsg.getSOAPPart().getEnvelope();  
            env.addNamespaceDeclaration("xsi", "http://www.w3.org/2001/XMLSchema-instance");  
            env.addNamespaceDeclaration("xsd", "http://www.w3.org/2001/XMLSchema");  
            //System.out.println(reqMsg.getSOAPPart().getContentId()+reqMsg.getSOAPPart().getContentLocation());  
            MimeHeaders mHers=reqMsg.getMimeHeaders();
            mHers.setHeader("SOAPAction", "http://WebXml.com.cn/getSupportCity");            
            /*String[] headers = mHers.getHeader("SOAPAction");
            for(String h:headers){
             System.out.println(h);
            }*/
            
            SOAPBody body=reqMsg.getSOAPBody();  
            SOAPElement qqCheckOnline=body.addChildElement("getSupportProvince","","http://WebXml.com.cn/");  
              
            SOAPElement qqCode=qqCheckOnline.addChildElement("byProvinceName");  
            qqCode.addTextNode(arg); 
            SOAPConnectionFactory conFac=SOAPConnectionFactory.newInstance();  
            SOAPConnection con=conFac.createConnection();
              
            reqMsg.writeTo(System.out);  
            SOAPMessage reply=con.call(reqMsg, "http://www.webxml.com.cn/WebServices/WeatherWebService.asmx");  
            System.out.println();  
            reply.writeTo(System.out);  
            
            
            NodeList l=(NodeList)reply.getSOAPBody().getChildNodes();  
            Node result=(Node)l.item(0);  
            System.out.println("\n"+result.getTextContent());
              
        } catch (SOAPException e) {  
            e.printStackTrace();  
        }    
       return reqMsg;  
   }
错误信息:soap:Server服务器无法处理请求。 ---> 未将对象引用设置到对象的实例。