title: Kivy Unknown class <NavigationDrawerIconButton>
body: <p>Trying kv using the example <a href="https://github.com/FranciscoCarbonell/kivymd-login-example" rel="nofollow noreferrer">https://github.com/FranciscoCarbonell/kivymd-login-example</a> but got `kivy.factory.FactoryException: Unknown class </p>
  <p>Problem is in</p>
  <pre><code>MainNavigationLayout:
      MDNavigationDrawer:
          id: navigation_drawer
          drawer_logo: &quot;menu.png&quot;
  
          NavigationDrawerIconButton:
              icon: &quot;home&quot;
              text: &quot;Inicio&quot;
              on_release: screen_manager.current = &quot;screen_inicio&quot;
  
          NavigationDrawerIconButton:
              icon: &quot;lock&quot;
              text: &quot;Pagina segunda&quot;
              on_release: screen_manager.current = &quot;screen_segundo&quot;
  </code></pre>