自学webservices，麻烦各位老师看下，为什么会出现这个错误

public static void main(String[] args){
         
        String url = "http://localhost:8080/axis2/services/AdminDao?wsdl";
        try {
            AdminDaoStub stub = new AdminDaoStub(url);
            AdminDaoStub.FindByCode af = new AdminDaoStub.FindByCode();
            af.setAdminCode("caocao");
            try {
                System.out.println(stub.findByCode(af).get_return());
            } catch (RemoteException e) {
                e.printStackTrace();
            }
        } catch (AxisFault e) {
            
            e.printStackTrace();
        }


org.apache.axis2.AxisFault: wrong number of arguments
    at org.apache.axis2.util.Utils.getInboundFaultFromMessageContext(Utils.java:531)
    at org.apache.axis2.description.OutInAxisOperationClient.handleResponse(OutInAxisOperation.java:375)
    at org.apache.axis2.description.OutInAxisOperationClient.send(OutInAxisOperation.java:421)
    at org.apache.axis2.description.OutInAxisOperationClient.executeImpl(OutInAxisOperation.java:229)
    at org.apache.axis2.client.OperationClient.execute(OperationClient.java:165)
    at org.tarena.service.AdminDaoStub.findByCode(AdminDaoStub.java:192)
    at org.tarena.test.TestServices.main(TestServices.java:18)