Select all if all checkboxes are selected, angular js

On my page I have angular ui accordion, inside of each panel, I'm rendering list with items and checkboxes, also I have checkbox "select all". For selection method and logic I used this resource. In this resource logic seems working, but however I'm putting this logic to my code, it stops working.

What I want to achieve is when all checkboxes are selected, checkbox "select all" has been selected automatically, and if some of checkboxes is unselect, checkbox "select all" has to be unselect as well.

I have tried multiple suggestions provided here, here, here, but in the end I'm getting the same result.

I appreciate if somebody could help me to resolve my problem.

 $scope.categories = [
{
  id: 1,
  name: "category 1"
},
 {
  id: 2,
  name: "category 2"
},
 {
  id: 3,
  name: "category 3"
}
]

               $scope.selectedAll = false;
                $scope.selectAll = function(array) {
                    $scope.selectedAll = !$scope.selectedAll;
                    angular.forEach(array, function(item) {
                        item.Selected = $scope.selectedAll;
                    });
                };

                $scope.checkIfAllSelected = function(array) {
                    $scope.selectedAll = array.every(function(item) {
                        return item.Selected == true
                    })
                };

html

<div>
<div class="row" ng-class="{'selected': selectedAll, 'default': !selectedAll}">
    <div>Select all
        <input type="checkbox"
               ng-model="selectedAll" ng-click="selectAll(categories)" >
    </div>
</div>
<div class="row" ng-repeat="item in categories | orderBy : 'id'" ng-class="{'selected': item.selected, 'default': !item.selected}">
    <div > 
        <input type="checkbox"
               ng-model="item.Selected" ng-click="checkIfAllSelected(categories)"
        >
    </div>
</div>

This is my plunker