Estou com erro na imagem do menu

Boa noite, preciso de ajuda com esse codigo. Já assisti a aula mais de 1 vez, olhei no forum e pra mim o codigo está correto. Porem fica os ... no canto. Não aparece o check, tive que criar meu menu na mão pois o meu android studio não criou. Abaixo meu codigo:

Manifest

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="br.studioapps.agenda">

    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:supportsRtl="true"
        android:theme="@style/AppTheme">
        <activity android:name=".ListaAlunosActivity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>

        </activity>
        <activity
            android:name=".FormularioActivity"
            android:label="@string/title_activity_formulario"
            android:theme="@style/AppTheme"
        >

        </activity>
    </application>

</manifest>

Formulario activity

public class FormularioActivity extends AppCompatActivity {

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

    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        MenuInflater inflater = getMenuInflater();
        inflater.inflate(R.menu.menu_formulario, menu);
        return super.onCreateOptionsMenu(menu);
    }
}

menu_formulario.xml

<?xml version="1.0" encoding="utf-8"?>
<menu xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res=auto"
xmlns:tools="http://schemas.android.com/tools"
tools:context="br.studioapps.agenda.FormularioActivity">

<item android:id="@+id/menu_formulario_ok"
    android:title="Ok"
    android:icon="@drawable/ic_confirmar"
    app:showAsAction="always" />
</menu>