$watchGroup in angularjs is not working - angularjs

Question

I am using ng-repeat to show items of objects in array, im using also filter with pagination.
in the below im using $watch to watch Filter.type.car and its work fine , but when i tried to watch Filter.type.car and Filter.type.Motorbike together using $watchGroup as below its now working.
$scope.currentPage = 0;
$scope.pageSize = 10;
$scope.getData = function () {
return $filter('filter')($scope.vichicles);
};
$scope.numberOfPages=function(){
return Math.ceil($scope.vichicles/$scope.pageSize);
};
$scope.$watchGroup(['Filter.type.car','Filter.type.motorbike'], function(term){
$scope.filtered = filterFilter($scope.vichicles, term);
$scope.getData = function () {
return $filter('filter')($scope.filtered)
};
$scope.numberOfPages=function(){
return Math.ceil($scope.getData().length/$scope.pageSize);
};
$scope.totalItems = $scope.filtered.length;
});
and this is the view
<div class="pagination">
<div class="pager">
<span class="current-page">{{currentPage+1}}</span>
<span class="total-pages">{{numberOfPages()}}</span>
</div>
<span class="total-items">{{totalItems}}</span>
<span class="item-description">Vichicles</span>
<button class="btn btn-clear arrow arrow-up" ng-disabled="currentPage == 0" ng-click="currentPage=currentPage-1">Previous</button>
<button class="btn btn-clear arrow arrow-down" ng-disabled="currentPage >= getData().length/pageSize - 1" ng-click="currentPage=currentPage+1">Next</button>
</div>
<ul class="list">
<li ng-repeat="v in vichicles | filter: search |searchFilter:Filter.type | searchFilter:Filter.level| startFrom:currentPage*pageSize | limitTo:pageSize">

Answer 1

Use separate Watch instead of watchGroup since those are not array
$scope.$watch('Filter.type.car', function() {
alert('hey, car has changed!');
});
$scope.$watch('Filter.type.motorbike', function() {
alert('hey, bike has changed!');
});