Android support action bar not showing overflow menu

My android app supports 2.2 and higher. I'm using the appcompat support library for the action bar, so it should only show if there are things that don't fit. I want my action bar to support the overflow button (the three vertical squares) that reveals a menu with the other items when clicked.

In my menu file, I have three items set up. However on the app I only see two of them, and the overflow button is not showing as well.

activity_menu.xml

<menu xmlns:android="http://schemas.android.com/apk/res/android" 
    xmlns:sord.ids_connect="http://schemas.android.com/apk/res-auto">

    <item
        android:id="@+id/action_settings"
        android:icon="@drawable/checkbox"
        android:title="@string/action_settings"
        sord.ids_connect:showAsAction="ifRoom" />

    <item
        android:id="@+id/action_settings2"
        android:icon="@drawable/checkbox_checked"
        android:title="@string/action_settings"
        sord.ids_connect:showAsAction="ifRoom" />

    <item
        android:id="@+id/action_settings3"
        android:icon="@drawable/ic_launcher"
        android:title="@string/action_settings"
        sord.ids_connect:showAsAction="ifRoom" />  

</menu>

java file

import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.support.v7.app.ActionBar;
import android.support.v7.app.ActionBarActivity;

public class Activity_Menu extends ActionBarActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_menu);

        ActionBar actionBar = getSupportActionBar();
        actionBar.setDisplayHomeAsUpEnabled(true);
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.activity_menu, menu);
        //return true;
        return super.onCreateOptionsMenu(menu);
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        switch (item.getItemId()) {
            case android.R.id.home:
                super.onBackPressed();
                return true;
        }
        return super.onOptionsItemSelected(item);
    }
}

manifest

    <activity
        android:theme="@style/Theme.AppCompat.Light.DarkActionBar"
        android:name="sord.ids_connect.Activity_Menu"
        android:screenOrientation="portrait"
        android:label="@string/title_activity_menu" >
    </activity>