For an angular-firebase setup , I have the following factory

.factory('ExpenseResource',function(UserService,$firebase){
    var ref=new Firebase("https://asdfsadf.firebaseio.com/company/"+UserService.company_name+'/days/'+UserService.today.toDateString()+'/expenses');
  return $firebase(ref);
});


and in the controller I have

    $scope.$watch('today',function(d){
      //Load all the expenses and advances
      ExpenseResource.$asArray().$loaded().then(function (exp) {
        $scope.expenses = exp;
      });
	});

But the ExpenseResource does not load for the second time when I change $scope.today : Why is that ?