Ionic gives blank screen when testing the app on real device

I have this app.js code in my Ionic App Project. It gives me a blank screen on start, but only when tested on a real device! When I use 'ionic serve' to test the app on the browser it works fine!

angular.module('orderApp', ['ionic'])
.config(function($stateProvider, $urlRouterProvider) {

    // Ionic uses AngularUI Router which uses the concept of states
    // Learn more here: https://github.com/angular-ui/ui-router
    // Set up the various states which the app can be in.
    // Each state's controller can be found in controllers.js
    //$stateProvide is like routeprovider in classic angularjs
    //It controlls the pages
    $stateProvider

    .state('categories', {
        cache: false,
        url: "/categories",
        templateUrl: "/templates/pages/categories/index.html",
        controller: "CategoriesIndexController"
    });

    // if none of the above states are matched, use this as the fallback
    $urlRouterProvider.otherwise('/categories');

});