Change language for bootstrap DatePicker/Angular

i hope ypu can help me.

First: I tried these things:

Change language for bootstrap DateTimePicker

Date format for bootstrap datepicker

But they dont work

Second: this is not my code, im just here to fix the bug. So maybe something is simply damaged and i just cant see it. :P

Ok lets start.

I have a datepicker which shows me the date. Casue we have our site in english and german (and they prefer different date styles) we have buttons to change the language with angular. We want the date to change too, like in this little example: http://jsfiddle.net/j7JMD/4/

Bu this just don't work.

First: this is my html

<div class="input-daterange input-group" id="datepicker">
<input type="text" class="form-control datepicker" name="fromDate" model="date.fromDate" datepicker>
<span class="input-group-addon">{{"REPORTS_DATEPICKER_UNTIL"| translate}}</span>
<input type="text" class="form-control datepicker" name="toDate" model="date.toDate" datepicker>
<span class="input-group-addon">
    <a ng-click="refreshSearchOverallReport()">
        <span class="glyphicon glyphicon-circle-arrow-right"></span>
    </a>
</span>

Now the js that load the datepicker in js:

function datepicker($parse, $cookieStore) {
return function (scope, element, attrs, controller) {
    var ngModel = $parse(attrs.model);
    ngModel(scope);
    var name = attrs.name + "Cookie";
    $(function () {
        var picker = element.datepicker({
            weekStart: 1,
            todayBtn: true,
            language: "en-EN",
            orientation: "top auto",
            calendarWeeks: true,
            autoclose: true,
            todayHighlight: true
        });
        picker.on('changeDate', function (e) {
            scope.$apply(function (scope) {
                // Change binded variable
                ngModel.assign(scope, e.date);
                $cookieStore.put(name, JSON.stringify(e.date));
            });
        });
        picker.datepicker('update', ngModel(scope));
    });
}};

the function will loaded at start over an angular directive

app.directive('datepicker', datepicker);

And last, i will have 2 Buttons to change language between german and english:

$scope.changeLanguageToGerman = function () {
$rootScope.language = "de-DE";
$cookieStore.put("language", "de-DE");
$translate.use($rootScope.language);
$('input.form-control.datepicker').datepicker({
    language: "de-DE"
});}

As you can see, i want to change the language zu german. But it still don't work and i get no error-message on the console.

I hope someone can help me :)