cookies 问题

function setAuthCookie($isCookies, $value) {
    if ($isCookies) {
        $expiration = time() + 3600;
    } else {
        $expiration = null;
    }
    $value .= '|' . $expiration . '|' . md5(COOKIE_KEY);
    $cookieName = COOKIE_NAME;
    setcookie($cookieName, $value, $expiration, '/');
    echo 'cookies: '.$_COOKIE[$cookieName]; //为啥是空的呢
}