why doesn't this code update my listadapter?

gistfile1.txt

here is my listadapter using an objectProperty:

class studentDetailsAdapter(ListAdapter):

        SDA = ObjectProperty(None)

        def __init__(self, **kwargs):
            super(studentDetailsAdapter, self).__init__(**kwargs)
            self.args_converter = lambda row_index, rec: {'text': rec,
                                            class studentDetailsAdapter(ListAdapter):

        SDA = ObjectProperty(None)

        def __init__(self, **kwargs):
            super(studentDetailsAdapter, self).__init__(**kwargs)
            self.args_converter = lambda row_index, rec: {'text': rec,
                                                        'size_hint_y': None,
                                                        'text_size': (200, 30),
                                            'deselected_color': [1, 1, 1, 1],
                                            'selected_color': [0, 0, 1, 1],
                                                        'font_size': 20,
                                                        'height': 50}
            'size_hint_y': None,
                                                        'text_size': (200, 30),
                                            'deselected_color': [1, 1, 1, 1],
                                            'selected_color': [0, 0, 1, 1],
                                                        'font_size': 20,
                                                        'height': 50}

this is the callback:

def callback(instance):

    try:
        detailsList= StudentDetail(lastname(instance.text), firstname(instance.text))
        SDA= studentDetailsAdapter(data= formatlist(detailsList), cls= ListItemLabel)
        print 'SDA data is', SDA.data
        StudentPhoto.source= photoName(detailsList[6])
        StudentPhoto.allow_stretch= True
        StudentPhoto.scale = 2
        return True
        
    except (IndexError, AttributeError):
        StudentPhoto.source= '/home/clyde/kids/765-default-avatar.png'
   

the callback prints to the terminal when my button is pressed but does not update the listadapter