Opera Not Saving Created Cookies

On my website I have a simple shop where you can add items to your cart. To make things nicer, we have Javascript to handle the process to make it faster. The problem I am having is that Opera does not save the cookie that the javascript creates.

Here's the relevant code:
Code:
function createCookie(name,value,days){
var expires = "";
if (days){
var date = new Date();
date.setTime(date.getTime()+(days*24*60*60*1000));
expires = "; expires="+date.toGMTString();
}else
expires = "";
document.cookie = name+"="+value+expires+"; path=/";
}

Full code: [URL]
You can see it live if you go to [URL] click on "Kaupa" (Icelandic for Buy) on any item. You will see a nice simple animation once you do. Once an item has been added, a cookie is created but in my Opera 10.53 the cookie does not exist. Browsing any other pages will result in the cart being empty. What am I doing wrong? Works for every other major browser except Opera.