xfire 调用webservice的时候返回[#document: null]这个事怎么回事呀？

xfire 调用.net webservice的时候返回[#document: null]这个事怎么回事呀？ Client client = new Client(
new URL(
"http://www.webxml.com.cn/WebServices/IpAddressSearchWebService.asmx?wsdl"));
HttpClientParams params = new HttpClientParams();
params.setParameter(HttpClientParams.USE_EXPECT_CONTINUE,
Boolean.FALSE);
params.setParameter(HttpClientParams.CONNECTION_MANAGER_TIMEOUT,
(long) 9000);
client.setProperty(CommonsHttpMessageSender.HTTP_CLIENT_PARAMS,
params);
Object[] obj = (Object[]) client.invoke("getCountryCityByIp", new Object[] {
"125.64.15.45" });