Up/Down buttons not working in simulator

I have been trying to use the  SDK. When I click the back button I get taken to the blue triangle but while my app is running none of the other buttons do anything. Here is the menu.xml file: 

<menu id="MainMenu">
    <menu-item id="item_1" label="@Strings.menu_label_1" />
    <menu-item id="item_2" label="@Strings.menu_label_2" />
</menu>

import Toybox.Lang;
import Toybox.System;
import Toybox.WatchUi;

class ArcadeMenuDelegate extends WatchUi.MenuInputDelegate {

    function initialize() {
        MenuInputDelegate.initialize();
    }

    function onMenuItem(item as Symbol) as Void {
        if (item == :item_1) {
            System.println("item 1");
        } else if (item == :item_2) {
            System.println("item 2");
        }
    }

}