Left Custom Button is not showing

//index.ios.js

``` javascript
renderScene (route, navigator) {
let Component = route.component;
let navBar = route.navigationBar;

if (navBar) {
navBar = React.cloneElement(navBar, { navigator, route, });
}
return (

{navBar}


);
}

render() {
return (

);
}
```

//...
//Login.js

``` javascript
onSignUp() {
this.props.navigator.push({
component: SignUp,
footerText: this.footerText(),
navigationBar: (
}
title={{title: "SIGN UP", tintColor: "white"}}
style={styles.navigator} />
)
});
}
```

//NavBarButton

``` javascript
export default class NavBarButton extends Component {

render() {
const { iconName, } = this.props;
const charmander = 'http://oyster.ignimgs.com/mediawiki/apis.ign.com/pokemon-blue-version/d/d4/Charmander.gif';
return (



);
}
}
```

I checked the example and followed it but the leftButton property doesn't get the custom button. Any suggestion?

Start with the navigation flow in index.ios.js and Login.js, then inspect how NavigationBar handles the leftButton prop supplied by the route. Reproduce the SignUp navigation with NavBarButton and compare it with the example; done means the custom button is visible in the navigation bar and responds to its onPress handler.

Written by the indexing model from the issue text.