Android: Ksoap2-android works on emulator (API 23) but not in tablet (API 19) -

i'm trying consume w3school testing web service, using ksoap2-android. here's code of asynctask:

private class myasynctask extends asynctask<integer, void, soapprimitive> {     @override     protected void onpreexecute() {         pgdprogress.show();     }     @override     protected soapprimitive doinbackground(integer... params) {         string soap_action = "http://www.w3schools.com/xml/fahrenheittocelsius";         string method_name = "fahrenheittocelsius";         string namespace = "http://www.w3schools.com/xml/";         string url = "http://www.w3schools.com/xml/tempconvert.asmx";          soapobject request = new soapobject(namespace, method_name);         request.addproperty("fahrenheit", params[0]);          soapserializationenvelope envelope = new soapserializationenvelope(soapenvelope.ver11);         envelope.dotnet = true;         envelope.setoutputsoapobject(request);          try {             httptransportse transport = new httptransportse(url);             transport.call(soap_action, envelope);             return (soapprimitive) envelope.getresponse();         } catch (exception e) {             log.e("test", "ksoap2", e);         }         return null;     }     @override     protected void onpostexecute(soapprimitive soapprimitive) {         pgdprogress.dismiss();         if(soapprimitive != null)             txvoutput.settext(soapprimitive.tostring());     } } 

it works on avd emulator (api 23) not on tablet (api 19). tablet's internet connection works because can navigate through google chrome. minimum sdk version of app project api 15.

log exception throw this:

01-27 10:28:14.604 10437-10601/com.android.wsconsumer e/test: ksoap2 

any ideas? sorry bad english, hope understand.