Mac: Drag and Drop Errors

I'm trying to do a simple drag and drop example:

so I have some sources (ImageViews)
and an AnchorPane as a target

then

@FXML
    void DragDetected(MouseEvent event) {


        ImageView n = (ImageView) event.getSource();
        Dragboard storeImage =n.startDragAndDrop(TransferMode.MOVE);
        ClipboardContent content = new ClipboardContent();
        content.putImage(n.getImage());
        storeImage.setContent(content);
        event.consume();

    }

this is the error I have:

'application/x-java-rawimage' is not a valid UTI string. Cannot set data for an invalid UTI.