Cookie is not set

When i try to connect to my forum . I succes to connect but when i change of page i lost my session and variable $disable_cookie is state false .I solve solution is replace this:

header('Set-Cookie: ' . $name_data . (($cookietime) ? '; Expires=' . $expire : '')
. '; path=' . $config['cookie_path']
. $domain
. ((!$config['cookie_secure']) ? '' : '; Secure') . ';' . (($httponly) ? ' HttpOnly' : ''), false);

to this:

setcookie($config['cookie_name'] . '_' . $name, $cookiedata, $cookietime,'/');