Kivy MD : line_color_normal Property Not Working

Question

I have made a dialog box in kivy MD and I have put an MDTextField inside it. Then, I tried to change the line_color_normal property in order to make the text field look cooler, but that didn't work.

class MyProgramApp(MDApp):
    def build(self):
        self.theme_cls.primary_palette = 'Red'
            return Builder.load_file('menu.kv')

    def pop_dialog(self, *args):
        input_box = BoxLayout(orientation='vertical', size_hint_y=None,
                             height=100, spacing=dp(5))
        self.text = MDTextField(hint_text='Name', max_text_length=25,
                            size_hint_x=0.9, line_color_normal=(1, 0, 0, 1))
        input_box.add_widget(self.text)
        self.dialog = MDDialog(title='Create a new card', type='custom',
                         content_cls=input_box, auto_dismiss=False)
        self.dialog.open()

I have looked at the documentation but it didn't help.