Retriving data from firebase using angularfire

i am trying to retrive data from firebase using angularfire, i got always an empty array, and no errors, could you please tell what am i doing wrong? Thanks in advance,

var app = angular.module('myApp',['firebase']);

app.config(function(){
    var config = {
        ...
    };
    firebase.initializeApp(config);
});

app.controller('myCtrl',['$scope','$firebaseArray', function($scope,$firebaseArray){
    console.log("my controller");
    var ref = firebase.database().ref().child('users');
    var list = $firebaseArray(ref);
    $scope.list = list;
    console.log('list: ' + $scope.list);
}]);