ok, well that makes a bit more sense, you did not include info that you had two different carts...
the success page only has the english cart page attached to it.
it also has this code to check if the cart is empty:
<?php
if ($eCart_en->IsEmpty()) {
$eCart_en->redirStr = "cart_en.php";
$eCart_en->cartAction = "RedirectIfEmpty";
}
?>
<?php
// WA eCart Redirect
if ($eCart_en->redirStr != "") {
header("Location: ".$eCart_en->redirStr);
}
?>
if the german cart is populated, this success page will direct to the english cart page because the english cart will be empty.