เขียน android ติดต่อเว็บ service asp.net แล้วคืนค่่าออกมาเป็นค่าว่างป่าว รบกวนช่วยดูให้หน่อยครับ

package com.prgguru.android;



import org.ksoap2.SoapEnvelope;
import org.ksoap2.serialization.SoapObject;
import org.ksoap2.serialization.SoapSerializationEnvelope;
import org.ksoap2.transport.HttpTransportSE;
import android.app.*;
import android.os.*;
import android.widget.TextView;

public class MainActivity extends Activity {
    /** Called when the activity is first created. */
    private static final String SOAP_ACTION = "http://192.168.1.4/ennergy/Service.asmx?WSDL/Hello";

    private static final String METHOD_NAME = "Hello";

    private static final String NAMESPACE = "";
    private static final String URL = "http://192.168.1.4/ennergy/Service.asmx?WSDL";
    TextView tv;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        tv=(TextView)findViewById(R.id.textView1);
        call();

    }

    public void call()
    {
        try {

            SoapObject request = new SoapObject(NAMESPACE, METHOD_NAME);

            request.addProperty("Hello2","Rajapandian");

            SoapSerializationEnvelope envelope = new SoapSerializationEnvelope(SoapEnvelope.VER11);
            envelope.dotNet=true;
            envelope.setOutputSoapObject(request);

            HttpTransportSE androidHttpTransport = new HttpTransportSE(URL);
            androidHttpTransport.call(SOAP_ACTION, envelope);

            Object result = (Object)envelope.getResponse();

            tv.setText(result.toString());
        } catch (Exception e) {
            tv.setText(e.getMessage());
            }
    }
}