Simple check all not working in AngularJS

I am trying to include a check all for my todo list, but once I hit toggleAll() it gets unchecked right away, plus it unchecks whichever one is already checked.

I really couldn't figure out why this behavior, perhaps some other things in the page are interfearing. A simple version of what I have included here is in this jsfiddle http://ift.tt/17mUYW8 and it is working.

<section id="main">
                <input id="toggle-all" type="checkbox" ng-model="selectedAll" ng-click="toggleAll()">
                <label for="toggle-all">Mark all as complete</label>
                <ul id="todo-list">
                    <li ng-repeat="todo in todos" ng-class="{'completed': todo.isCompleted=='true'}" class="editing">
                        <div class="view" >
                            <input class="toggle" type="checkbox" ng-click="complete(todo)" ng-model="todo.isCompleted" ng-checked="{{todo.isCompleted}}" ng-true-value="'true'"  ng-false-value="'false'">
                            <label ng-hide="isEditing" ng-dblclick="isEditing = !isEditing">{{todo.title}}</label>
                            <button class="destroy" ng-click="remove(todo)"></button>
                        </div>
                        <input class="edit" ng-show="isEditing" ng-model="todo.title" ng-blur="isEditing = !isEditing;edit(todo);">
                    </li>
                </ul>
            </section>

Controller

 $scope.toggleAll = function () {
    if ($scope.selectedAll) {
        $scope.selectedAll = true;
    } else {
        $scope.selectedAll = false;
    }
    angular.forEach($scope.todos, function (todo) {
        todo.isCompleted = $scope.selectedAll;
    });
};

Any help is appreciated.