Notification redirecting to white screen

I am working on a cart set-up. I use a custom theme. I use Add to Cart Tweaks. I am on Drupal 6 (yeah I know)
The JS files are there.

I use a View with the "Buy it now" button.

Now, when I invoke the module with :

 <?php $block = module_invoke('uc_ajax_cart', 'block', 'view', '0');
    print($block['content']); ?>

I do get the Cart, and I can add a product. But there isn't much Ajax going on I am noticing. When I remove a product I get redirected to a white screen :
"Product X succesfully removed from Cart"

The URL layout is :
http://www.example.com/uc_ajax_cart/remove/item?nid=52&destination=node%...

Any debugging help would be appreciated. Normally at this stage things start to work ;-)