passing discounts to secure server

Hi there, I've successfully set up a discount coupon system based on your instruction in the following post which was very useful:
showthread.php?t=19042&highlight=coupon

However I'd like some addition information on the following:
1. Can I set the error message to display if the code has expired or is it best to simply remove the discount from the eCart object on expiry?

2. I'm having problems getting my discount to pass over to the secure server. Not sure if this is an issue with the cart page or the confirm. I've attached both and would be very grateful if you could let me know what I've done wrong.

Many thanks.

1) You could add an if condition to show the message:

<?php if(isset($_SESSION['PromoCode']) && isset($_SESSION['realCode']) && ($_SESSION['PromoCode'] != $_SESSION['realCode']) || date("m/d/Y") > "4/12/2012") { ?>
the promo code entered did not match
<?php } ?>


2) use an htaccess rule to force the site to use the secure server for all pages to prevent transfer problems:
force-ssl-htaccess.html

hiya, thanks for this. Trouble is I don't really want to force them to use the secure server as the site is quite large and I don't want it to get too slow. Can I pass the promo code to the secure server in the same way that the cart contents are transferred. On the cart page i tried putting this in before the secure checkout button:
<input type="hidden" name="CouponCode" id="CouponCode" value="txtPromoCode>" />
And then on my checkout page i tried adding this at the top:
<?php
if (!session_id()) session_start();
if((((isset($_POST["txtPromoCode"]))?$_POST["txtPromoCode"]:"") != "")) {
$_SESSION["PromoCode"] = "".((isset($_POST["txtPromoCode"]))?$_POST["txtPromoCode"]:"") ."";
}
?>
As I thought this would start the session on the secure server with the entered value from the cart page - but it doesn't seem to want to work - can you tell me what I'm doing wrong.
Many thanks.

Actually I need to to correct that. I've now tried this as my hidden form field:
<input type="hidden" name="PromoCode" id="PromoCode" value="$_SESSION["PromoCode"]" />

And this on my checkout page in my attempt to load the session promo code:
<?php
if (!session_id()) session_start();
if("" == "") {
$_SESSION["PromoCode"] = "".((isset($_POST["PromoCode"]))?$_POST["PromoCode"]:"") ."";
}
?>

As I thought that was slightly more intelligent - still doesn't work though!

Ok - after a bit more head scratching I have now figured this out. So for anyone else who's interested this code works:

On the cart page the hidden form field which should be immediately before the checkout button, ie outside the repeat region:
<input type="hidden" name="PromoCode" id="PromoCode" value="<?php echo((isset($_SESSION["PromoCode"]))?$_SESSION["PromoCode"]:"") ?>" />

And on the checkout page the code to receive the promo code should be this:
<?php
if (!session_id()) session_start();
if("" == "") {
$_SESSION["PromoCode"] = "".((isset($_POST["PromoCode"]))?$_POST["PromoCode"]:"") ."";
}
?>