android调用java的webservices返回结果null

[sxxdll]

String code = "",soapAction=GlobalConts.URL_POST+methodname;
		//GlobalConts.URL_POST:http://ws.syzs.newland.com/
		//methodname=validateUserInfo
		
		SoapSerializationEnvelope envelope = new SoapSerializationEnvelope(
				SoapEnvelope.VER11);

		SoapObject request = new SoapObject(GlobalConts.URL_POST, methodname);

		try {
			request.addProperty("UserId", uname);
			request.addProperty("Id", uid);
			request.addProperty("password", upwd);

			// request.addProperty("filestrs", tag);

			envelope.bodyOut = request;
			envelope.dotNet = false;
			envelope.encodingStyle = "UTF-8";
			envelope.setOutputSoapObject(request);
		} catch (Exception e1) {
			// TODO Auto-generated catch block
			Log.e("Error", "1");
		}

		try {
			AndroidHttpTransport ht = new AndroidHttpTransport(GlobalConts.URl_File);
			ht.debug = true;
			ht.call(soapAction, envelope);
			
			if (envelope.getResponse() != null) {
				SoapObject result = (SoapObject) envelope.bodyIn;
				// String name = result.getProperty(0).toString();
				// Object detail = (Object) result.getProperty(0);
				if (result != null) {
					code = result.toString();
				}
			}
		} catch (Exception e) {
			e.printStackTrace();
		}
		return code;

调用webservices结果ht.call(soapAction, envelope);返回空。调试了好多遍，不知道什么原因。测试平台android4.4+求大神帮忙。谢谢。