sharedpreferences does not update
<p>I've a code to change a duration of animation, at first start of program "preferenze" runs to read sharedpreferences, later, users can change duration of animation by Preferences.class. Seems ok but I can't update preferences, my code:</p>

<pre><code>@Override
    public void onCreate(Bundle savedInstanceState){ 
      super.onCreate(savedInstanceState);
</code></pre>

<p>// runs every time app starts</p>

<pre><code>preferenze();
</code></pre>

<p>// read shared
    private void preferenze() {</p>

<pre><code>        SharedPreferences prefs = PreferenceManager.getDefaultSharedPreferences(getBaseContext());
        CheckboxPreference = prefs.getBoolean("checkboxPref", true);
        String ListPreference = prefs.getString("listpref", "1500");


public boolean onCreateOptionsMenu(Menu menu) {

menu.add("Impostazioni").setOnMenuItemClickListener(new OnMenuItemClickListener() {
            public boolean onMenuItemClick(MenuItem item) {
                    //Toast.makeText(getApplicationContext(), "Vai al Racconto... Non attivo", Toast.LENGTH_SHORT).show();
                    //goToPage();
                Intent settingsActivity = new Intent(getBaseContext(),
                        Preferences.class);
        startActivity(settingsActivity);

public void onSharedPreferenceChanged(SharedPreferences prefs,
            String listpref) {
        Toast.makeText(getApplicationContext(), "eseguo changed: "+listpref, Toast.LENGTH_SHORT).show();
          if (fade == 500){
            animazione = R.style.MyCustomTheme1;
        }
        else if (fade == 1000){
            animazione = R.style.MyCustomTheme2;
        }
        else if (fade == 1500){
            animazione = R.style.MyCustomTheme3;
        }
        else if (fade == 2000){
            animazione = R.style.MyCustomTheme4;
        }

    }
</code></pre>

<p>Manifest:</p>

<pre><code>&lt;uses-sdk
    android:minSdkVersion="7"
    android:targetSdkVersion="17" /&gt;
</code></pre>
