Shopify API + add.js + 404 by David Nejedly

Hi, I've been bashing my head against the screen all morning trying to figure out why I'm getting a 404 error by using a post as described here (http://docs.shopify.com/support/your-website/themes/can-i-use-ajax-api) to add items to the cart...

What the final goal is, is to add multiple items to the car with 1 button click.

I've scoured the forum and found similar requests, none with a definite solution? I've asked live shopify chat who couldn't help so I'm hoping that someone can point me in the right direction.

We have a customised shopify theme based on the standard 'Minimal theme'.

When running this code:

Shopify.itemsToAdd = [];
 Shopify.addItemstoTheCart = function() {
  if (Shopify.itemsToAdd.length) {
    var item = Shopify.itemsToAdd.pop();
    $.ajax({
      url: '/cart/add.js',
      dataType: 'json',
      type: 'post',
      data: item,
      success: Shopify.addItemstoTheCart,
      error: Shopify.addItemstoTheCart
    });
  } else {
    //window.location.href = '/cart';
    alert('redirecting to cart');
  }

I get a 404 as shown in the firebug inspector

Remote Address:204.93.213.54:80
Request URL:http://the-nutritionists-3.myshopify.com/cart/add.js
Request Method:POST
Status Code:404 Not Found
Request Headersview source
Accept:application/json, text/javascript, */*; q=0.01
Accept-Encoding:gzip,deflate,sdch
Accept-Language:en-US,en;q=0.8
Connection:keep-alive
Content-Length:23
Content-Type:application/x-www-form-urlencoded; charset=UTF-8
Cookie:cacheable_token=753a1ad0-bf11-4d48-ba52-9409852fe550; ki_u=dd2bf8c7-b211-74ce-95b4-c5c5bc62c646; ki_r=https%3A//delivery.shopifyapps.com/login/authenticate%3Fshop%3Dthe-nutritionists-3.myshopify.com; ki_s=120557%3A0.0.0.0.1; __atuvc=2%7C20%2C0%7C21%2C2%7C22%2C0%7C23%2C1%7C24; cart=9e7f42b87543a0e84b9165f491a3b483; ki_t=1403230130419%3B1404256168436%3B1404256681477%3B3%3B28; _session_id=56327072167c1d0ba915fb8782146129; admin_next_beta_domains=true; _ab=1; _ga=GA1.2.81915067.1397696914; __utma=1.81915067.1397696914.1404707052.1404771793.28; __utmc=1; __utmz=1.1402617312.1.1.utmcsr=(direct)|utmccn=(direct)|utmcmd=(none); storefront_digest=f6a73da942049ff8e0f85b80b17b5d5852f94972; ki_t=1403230130419%3B1404771851587%3B1404771851587%3B4%3B29; ki_r=; request_method=GET; _shopify_y=c69f41ad-0ab4-4e89-828f-fba0f6a2420c; _shopify_visit=t; _shopify_uniq=x; _shopify_s=72236e5e-dbc9-4e09-82ba-7d95fa546898
Host:the-nutritionists-3.myshopify.com
Origin:http://the-nutritionists-3.myshopify.com
Referer:http://the-nutritionists-3.myshopify.com/collections/bundle-1/products/bonvit-psyllium-husks
User-Agent:Mozilla/5.0 (Windows NT 6.1) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/35.0.1916.153 Safari/537.36
X-Requested-With:XMLHttpRequest

What is strange is that accessing change.js (http://the-nutritionists-3.myshopify.com/cart/change.js) is OK but http://the-nutritionists-3.myshopify.com/cart/add.js gives a 404....

Any information on what is going on here would be great... At this stage I'm thinking that the minimal theme is the cause and somehow missing the /cart/add.js file...?

UPDATE: the response found is this

{"status":404,"message":"Cart Error","description":" Cannot find variant (request_id: d03a5117-b88f-4453-86a8-30e5985b3ada)"} 

so it seems like a variant issue as described here http://ecommerce.shopify.com/c/ecommerce-design/t/shopify-additem-404-error-54782

I will keep investigating but if anyone has experienced this please let me know how you overcame the problem.

ANY help is greatly appreciated.

Regards,

David