Adding elements dynamically to an array

I was following a simple angular tutorial that basically shows a list of elements on the browser for a hard-coded array, and creates a form that adds more elements to this array and adds the new created elements on the browser directly.
After writing my code, I tried to add a new element to the array, but the implementation only adds a new element <li> without the title of it

see my code here on jsfiddle
https://jsfiddle.net/SaifHarbia/ht4jme7q/1/
the code is also posted below

my html

    <div ng-app="bookmark" ng-controller="BookCtrl">
    <ul>
    <li ng-repeat="bookmark in bookmarks">
        <a href="#" ng-click="setCurrentCategory(bookmark)">
     {{bookmark.title}}  </a>
    </li>

   </ul>
    <button type="button" ng-click="startCreating();" class="btn btn-link">
        <span class="glyphicon glipbicon-plus"></span>
        Create Bookmark
    </button>
    <br><hr/>
    <form class="create-form" ng-show="isCreating" role="form" 
    ng-submit="createBookmark(newBookmark)" novalidate>
        <div class="form-group">
            <label for="newBookmarkTitle">Bookmark Title</label>
            <input type="text" class="form-control" id="newBookmarkTitle"
      ng-mode="newBookmark.title" placeholder="Enter title">
        </div>
        <div class="form-group">
            <label for="newBookmarkURL">Bookmark URL</label>
            <input type="text" class="form-control" id="newBookmarkURL" 
     ng-mode="newBookmark.url" placeholder="Enter URL">
        </div>

        <button type="submit" class="btn btn-info btn-lg">Create</button>
        <button type="button" class="btn btn-default btn-lg pull-right" 
    ng-click="cancelCreating()">Cancel</button>
    </form>
        </div>

my javascript:

var app=angular.module("bookmark", []);

app.controller("BookCtrl", function($scope){

    $scope.bookmarks=[
        {title: "Type1", url: "http://www.somewebsite.com/"},
        {title: "Type2", url: "http://www.website.com/"}
    ]
    function resetCreateForm(){
        $scope.newBookmark={
            title : '',
            url:''     
        }
    }
    $scope.isCreating= false;
    function startCreating(){
        $scope.isCreating=true;

        resetCreateForm();
    }

    function cancelCreating(){
        $scope.isCreating = false;
    }

    function createBookmark(bookmark){

            $scope.bookmarks.push(bookmark);


            resetCreateForm();
        }
    $scope.startCreating= startCreating;
    $scope.cancelCreating=cancelCreating;
    $scope.createBookmark= createBookmark;
});