recaptcha: Validation always NOT CORRECT

I followed the installation and set up successfully, but when I tried it correctly (Check the “Im not a robot”), it always says, The g-recaptcha-response field is required. What happened to that?

Need Help guys. btw Im using Laravel 5.1

Heres my code

Form:

<div class="form-group{{ $errors->has('g-recaptcha-response') ? ' has-error' : '' }}">
	{!! Recaptcha::render() !!}
	@if($errors->has('g-recaptcha-response'))
		<span class="help-block">
			{{ $errors->first('g-recaptcha-response') }}
		</span>
	@endif
</div>

===================================================================

Validation

$this->validate($request, [
	'username' => 'required',
	'password' => 'required|min:6',
	'password_again' => 'required|same:password',
	'email' => 'required|email|max:255',
	'g-recaptcha-response' => 'required|recaptcha'
]);