Up indicator does not show up
<p>I'm currently trying to enable <a href="http://developer.android.com/guide/topics/ui/actionbar.html#Up" rel="nofollow">up navigation</a> in my Android app.
To do so, I followed the tutorial and implemented the necessary code into my activity:</p>

<h2>SettingsActivity.java</h2>

<pre><code>package de.ntraum.arcon;

import android.content.Intent;
import android.os.Bundle;
import android.preference.PreferenceActivity;
import android.view.MenuItem;

public class SettingsActivity extends PreferenceActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        getActionBar().setHomeButtonEnabled(true);
        addPreferencesFromResource(R.xml.settings);
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        switch (item.getItemId()) {
        case android.R.id.home:
            startActivity(new Intent(SettingsActivity.this, MainActivity.class)
                    .addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP));
            return true;

        default:
            return super.onOptionsItemSelected(item);
        }
    }

}
</code></pre>

<p>If relevant, here's the <code>AndroidManifest.xml</code> and <code>styles.xml</code>:</p>

<h2>AndroidManifest.xml</h2>

<pre><code>&lt;manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="de.ntraum.arcon"
    android:versionCode="1"
    android:versionName="1.0" &gt;

    &lt;uses-sdk
        android:minSdkVersion="14"
        android:targetSdkVersion="15" /&gt;

    &lt;application
        android:icon="@drawable/ic_launcher"
        android:label="@string/app_name"
        android:theme="@style/Light" &gt;
        &lt;activity
            android:name=".MainActivity"
            android:label="@string/title_activity_main" &gt;
            &lt;intent-filter&gt;
                &lt;action android:name="android.intent.action.MAIN" /&gt;

                &lt;category android:name="android.intent.category.LAUNCHER" /&gt;
            &lt;/intent-filter&gt;
        &lt;/activity&gt;
        &lt;activity
            android:name=".SettingsActivity"
            android:exported="false"
            android:label="@string/title_activity_settings" &gt;
            &lt;intent-filter&gt;
                &lt;category android:name="android.intent.category.PREFERENCE" /&gt;
            &lt;/intent-filter&gt;
        &lt;/activity&gt;
    &lt;/application&gt;

&lt;/manifest&gt;
</code></pre>

<h2>styles.xml</h2>

<pre><code>&lt;resources&gt;

    &lt;style name="Light" parent="android:Theme.Holo.Light.DarkActionBar" /&gt;

    &lt;style name="Dark" parent="android:Theme.Holo" /&gt;

&lt;/resources&gt;
</code></pre>

<h2>Issue</h2>

<p>The thing is, when accessing the activity, the up indicator in the action bar is missing. Nevertheless, the navigation is actually working (it takes me back to the <code>MainActivity.class</code>), it's just the small indicator that does not show up correctly.</p>

<p><img src="http://i.stack.imgur.com/tMsY6.png" alt="Screenshot of Activity with missing up indic"></p>

<p>I've tested it on my own device and in the emulator so far.</p>
