public function isValid()
	{
	  	// Skip without submission
		if (strtoupper($_SERVER['REQUEST_METHOD']) !== 'POST') {

			return FALSE;

		} else {

			$captchaChallenge = isset($_POST['recaptcha_challenge_field'])
				? $this->_sanitizeField($_POST['recaptcha_challenge_field'])
				: NULL;

			$captchaResponse  = isset($_POST['recaptcha_response_field'])
				? $this->_sanitizeField($_POST['recaptcha_response_field'])
				: NULL;
		 	// Skip empty submission
			if ( strlen($captchaChallenge) == 0 || strlen($captchaResponse) == 0 ) {
				$this->setError('incorrect-captcha-sol');
				return FALSE;
			}

			$data = array(
				'privatekey' => $this->_privateKey,
				'remoteip'   => $this->_remoteIp(),
				'challenge'  => $captchaChallenge,
				'response'   => $captchaResponse
				);

			$result = $this->_postHttpChallenge($data);

			if ( $result['isvalid'] === "true") {
				return TRUE;

			} else {
				$this->setError($result['error']);
			}
			return FALSE;
		}
	}