HTTPClient Exception

package com.ELQuiz;

import org.apache.http.client.HttpClient;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.impl.client.DefaultHttpClient;

import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;


public class EndActivity extends Activity
{

    public void onCreate(Bundle savedInstanceState) 
    {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.end);
        
        Intent intent = getIntent();
        Bundle daten = intent.getExtras();
        
        int richtig = daten.getInt("Richtig");
        float zeit = daten.getFloat("Zeit");
        String user = daten.getString("User");
        
        float points = 1000 - ((10-richtig)*10) - (zeit/1000);

        
        
        TextView ergebnis = new TextView(this);
        ergebnis = (TextView) findViewById(R.id.ergebnis_textview);
        
        ergebnis.setText(user + " hat beim Elektronik-Quiz " + richtig + " von 10 Fragen in einer Zeit von " + (zeit/1000) + " Sekunden richtig beantwortet und damit " + points + " Punkte erreicht.");
        
        //MySQL
        
        try{
            HttpClient httpclient = new DefaultHttpClient();
            HttpPost httppost = new HttpPost("http://www.example.com/el_quiz/on_db.php");
            httpclient.execute(httppost);
        }

        catch(Exception e)
        {
            ergebnis.setText(e.toString());
        }
        
        //MySQL Ende
        
        Button end = new Button(this);
        end = (Button) findViewById(R.id.Button_Restart);
        end.setOnClickListener(new View.OnClickListener() 
        {
            
            public void onClick(View v) 
            {                
                Intent myIntent = new Intent(v.getContext(),ELQuizActivity.class);
                startActivity(myIntent);    
            }
            
        });
        
        
        
    }
}