I am not able to REFOCUS TextInput after reload of my screen

[Surendrababu Nallagorla]

When I reload the screen, I am able to clear TextInut, but not able to REFOCUS, help me  to fix my following code?

from kivy.app import App

from kivy.lang import Builder

from kivy.uix.screenmanager import ScreenManager, Screen

Builder.load_string('''

<MainScreen>:

BoxLayout:

orientation: 'vertical'

BoxLayout:

BoxLayout:

TextInput:

id: Image_Input

multiline: False

focus: True

on_text_validate: Image_Input.focus=True

Button:

on_press:Image_Input.focus=True

text: 'RELOAD'

on_press: root.reload(); Image_Input.text='' 

''')

class MainScreen(Screen):

def reload(self):

print("screen reloaded")

pass

class TestApp(App):

    def build(self):

        # Create the screen manager

        screenManager = ScreenManager()

        screenManager.add_widget(MainScreen(name='main'))

        return screenManager

if __name__ == '__main__':

    TestApp().run()