Datepicker getData Angular + Firebase

I have a problem with getting data from datepicker inputbox into database.

I have a form

<form name="myForm">

 <div>

    <input type="text" name="todoNameField" ng-model="todoName" placeholder="wat do" required ng-minlength="1" class="form-control"
            ng-keyup="($event.keyCode == 13 && todoName.length > 0) ? addItem() : return" style="width: 50%; margin-bottom: 10px"/>

    <h4>Deadline?</h4>
    <div class="row">
    <div class="col-md-6">
        <p class="input-group">
          <input type="text" class="form-control" datepicker-popup="{{format}}" ng-model="dt" is-open="opened" min-date="minDate" datepicker-options="dateOptions" date-disabled="disabled(date, mode)" ng-required="true" close-text="Close" />
          <span class="input-group-btn">
            <button type="button" class="btn btn-default" ng-click="open($event)"><i class="glyphicon glyphicon-calendar"></i></button>
          </span>
        </p>
    </div>
    </div>

     <button ng-click="addItem()" ng-hide="myForm.todoNameField.$invalid" class="btn btn-primary" type="button">Save</button>
 </div>

 </form>

And a controller with a function that handles adding new items

    $scope.addItem  = function () {

    // Create a unique ID
    var timestamp = new Date().valueOf();

    // Get the Firebase reference of the item
    var itemRef = new Firebase(FIREBASE_URL + timestamp);

    $firebase(itemRef).$set({
        id: timestamp,
        name : $scope.todoName,
        dt : $scope.dt, // <<< date
        completed: false
    });

    $scope.todoName = "";
    $scope.dt = "";

}

If I remove dt : $scope.dt everything is stored nicely and there is no problem with using it later, however when I try to store the date it's not working. It's not even adding a dt: in a database.. not even empty. Is there something I'm missing with adding a value from datepicker? I thought I can grab it like the input "todoName", but It doesn't seem to be working.

Thx for help.