Pressed android button state

I've been following a tutorial that explains how to use background for a button with different states but it doesn't seem to work :S

Here is my code :

    <?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android">
    <item android:drawable="@drawable/boutonn" android:state_window_focused="false"/>
    <item android:drawable="@drawable/boutonnpousse" android:state_pressed="true"/>
    <item android:drawable="@drawable/boutonnpousse" android:state_focused="true"/>
    <item android:drawable="@drawable/boutonn" android:state_focused="false" 
    android:state_pressed="false" />

</selector>

This is an xml code that I've placed in my drawable folder, here is a part of the xml of the activity that uses these buttons :

    <?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="@drawable/backgrounddd"
    android:orientation="vertical" >

            <Button
                android:id="@+id/bNoteRemind"
                android:layout_width="100dp"
                android:layout_height="100dp"
                android:layout_gravity="center"
                android:background="@drawable/imagebutton1" /> 
    ...

And here is the java class :

public class MenuPrincipal extends Activity {

    Button NoteRemind;          

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        // TODO Auto-generated method stub
        super.onCreate(savedInstanceState);

        //on lui associe le layout menuprincipal.xml
        setContentView(R.layout.menuprincipal);

        NoteRemind = (Button) findViewById(R.id.bNoteRemind);     

        // Si on choisit de rédiger une nouvelle task on va être rediriger sur l'activité NoteReminder

        NoteRemind.setOnClickListener(new View.OnClickListener() {

            public void onClick(View v) {
                // TODO Auto-generated method stub

                //On créé l'Intent qui va nous permettre d'afficher l'autre Activity
                //Mettez le nom de l'Activity dans la quelle vous êtes actuellement pour le premier parametre
                v.setPressed(true);

                Intent intent = new Intent(MenuPrincipal.this, NoteReminder.class);
                //Intent intent = new Intent(MenuPrincipal.this, Teste2.class);
                //On démarre l'autre Activity
                startActivity(intent);


            }
        }); ....

The button displays well but when I press it it doesn t show the pressed image :s I don't understand what I am doing wrong !

Does anyone see an error somewhere ???

Where should I put those lines ? I ve put them in my button xml

    <Button
        android:id="@+id/bNoteRemind"
        android:layout_width="100dp"
        android:layout_height="100dp"
        android:layout_gravity="center"
        android:background="@drawable/imagebutton1"
        android：focusable="true"
        android:focusableInTouchMode="true" />

But now my button background changed to the pressed image without me pressing it :p and it doesn't change

Is the Button the only thing you have displayed in your Activity? If so, then it will be focused (triggering the third item in your selector) when the window loads, and you won't be able to navigate away from it. If you want to change only when pressed, delete that third line. While you're at it, delete the first line, as the button will never be pressed when the window isn't focused.

In fact, I suggest this code:

<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android">
    <item android:drawable="@drawable/boutonnpousse" android:state_pressed="true"/>
    <item android:drawable="@drawable/boutonn"/>
</selector>