php shopping cart - session

[nzfade]

Hi, I recently built a php shopping cart off the http://www.adobe.com/devnet/dreamweaver/articles/php_cart.html  website.  I got it working with my own website, and left it a few weeks.  After adding several individual pages full of products.....for example, product_glass.php, product_acrylics.php the shopping cart seems to have fallen over itself.

 

Basically the session seems to start again, every time i click on adding a new product.  Also, when updating the amount of items per product, it fails as well. 

 

Any idea's on what I need to keep the same session open per page, would be hugely appreciated.

 

in the database file i'm using the following code

 

function GetCartId()

{

// This function will generate an encrypted string and

// will set it as a cookie using set_cookie. This will

// also be used as the cookieId field in the cart table

if(isset($_COOKIE["cartId"]))

{

return $_COOKIE["cartId"];

}

else

{

// There is no cookie set. We will set the cookie

// and return the value of the users session ID

 

session_start();

setcookie("cartId", session_id(), time() + ((3600 * 24) * 30));

return session_id();

 

 

as well as include 'db.php';  to call this, at the top of each page, ie product_glass.php..........product_details.php (with the information from the glass), and the cart.php function......

 

the cookie generates a random code thats saved, and every time i update, or add a new product, the database is updated with a new cookie number......any hints or help would be hugely appreciated.

 

Thanks in advance