google recaptcha returns false due to "invalid-input-secret"

I have installed the latest recaptcha from google but it always returns false upon post submit and always returning "invalid-input-secret" error even though the verification is always correct from the frontend view. What could be the reason on this. Btw I am testing everything in localhost xampp with phalcon framework. Here is the part where I check the captcha:

protected function validate_data($post, $ip){

    $validation = new Validation();
    $validation->add(
        'user_name',
        new PresenceOf(
            array(
                'message' => 'The Username is required'
            )
        )
    );
    $validation->add(
        'email',
        new PresenceOf(
            array(
                'message' => 'The e-mail is required'
            )
        )
    );
    $validation->add(
        'password',
        new PresenceOf(
            array(
                'message' => 'The Password is required'
            )
        )
    );
    $validation->add(
        'cpassword',
        new PresenceOf(
            array(
                'message' => 'The Confirmation Password is required'
            )
        )
    );
    $validation->add(
        'email',
        new Email(
            array(
                'message' => 'The e-mail is not valid'
            )
        )
    );

    $validation->add('password', 
        new Confirmation(array(
           'message' => 'Password doesn\'t match confirmation',
           'with' => 'cpassword'
           )
        )
    );

    $error = $validation->validate($post);
    $errors = array();
    if(count($error)){
        foreach($error as $e){
            $errors[] = $e;
        }
    }

    $data = array(
        'secret' => "my secret key",
        'response' => $post['g-recaptcha-response'],
        'remoteip' => $ip
    );

    $verify = curl_init();
    curl_setopt($verify, CURLOPT_URL, "https://www.google.com/recaptcha/api/siteverify");
    curl_setopt($verify, CURLOPT_POST, true);
    curl_setopt($verify, CURLOPT_POSTFIELDS, http_build_query($data));
    curl_setopt($verify, CURLOPT_SSL_VERIFYPEER, false);
    curl_setopt($verify, CURLOPT_RETURNTRANSFER, true);
    $res = curl_exec($verify);

    $captcha = json_decode($res);

    if($captcha->success == false){
        $errors[] = "Invalid Captcha, You are a freakin robot!";
    }

    return $errors;

}

what could be the reason here? here is the output when you dump the response:

object(stdClass)#70 (2) { ["success"]=> bool(false) ["error-codes"]=> array(1) { [0]=> string(20) "invalid-input-secret" } } 

Silly me, I doubled check the secret key and it was just missing a single character at the beginning. That solved it.