PHP cookie问题？

ini_set(”output_buffering”, “1″);
session_start();
//echo $_SESSION['code'];
//定义一个常量，用来授权调用
define('IN_TG', true);

//定义一个CSS调用常量
define('SCRIPT', 'login');

require dirname(__FILE__).'/includes/common.inc.php';//获取当前路径

//开始处理登录状态
if ($_GET['action'] == 'login'){
    //防止恶意注册，跨站攻击
    _check_code($_POST['code'] , $_SESSION['code']);
    //引入验证文件
    include ROOT_PATH.'includes/login.func.php';   
   
    //开始接受数据
    $_clean = array();
    $_clean['username'] = _check_user($_POST['username'],2,20);
    $_clean['password'] = _check_password($_POST['password'], 6);
    $_clean['time'] = _check_time($_POST['time']);
    //print_r($_clean);
   
    //到数据库验证
    if (!!$_rows = _fetch_array("SELECT gt_username,gt_uniqid FROM gt_user WHERE gt_username='{$_clean['username']}' AND gt_password='{$_clean['password']}' AND gt_active='' LIMIT 1")){
        /*echo '登录成功！';
        echo $_rows['gt_username'];
        echo $_rows['gt_uniqid'];*/
        
        _close_db();//关闭数据
        _session_destroy();//销毁 session
        _setcookies($_rows['gt_username'], $_rows['gt_uniqid']);//调用 cookie函数
        //setcookie('username',$_rows['gt_username']);
        //setcookie('uniqid',$_rows['gt_uniqid']);
        //跳转方法一
        //_location('登录成功!', 'index.php');
    //跳转方法二,还是有点问题
        _location(null, 'index.php');
    } else {
        _close_db();
        _session_destroy();
        _location('用户名密码不匹配，或者该账户未被激活!','login.php');
    }
}

//这个登录成功后跳转到首页上的函数
function _location($_info,$_url){
    if (!empty($_info)){
        echo "<script type='text/javascript'>alert('$_info');location.href='$_url';</script>";
        exit();
        //echo "<script type='text/javascript'>alert('".$_info."');history.back();</script>";
        //exit;
    } else {
        header('Location:'.$_url);        
    }
}
//这个是设置COOKIE的函数
/**

 * 生成 cookies

 * Enter description here ...

 */
function _setcookies($_username,$_uniqid){
    setcookie('username',$_username);
    setcookie('uniqid',$_uniqid);
}