Hi Gergely,
thank you for your answer.
I didn´t understand the solution given above, for me it seemed there is some information missing. But i found the point in my shop.
This change in my application_top helped:
case 'add_product' : if (isset($HTTP_POST_VARS['products_id']) && is_numeric($HTTP_POST_VARS['products_id'])) {
$attributes = isset($HTTP_POST_VARS['id']) ? $HTTP_POST_VARS['id'] : '';
$cart->add_cart($HTTP_POST_VARS['products_id'], $cart->get_quantity(tep_get_uprid($HTTP_POST_VARS['products_id'], $attributes)), $attributes);
// original: $cart->add_cart($HTTP_POST_VARS['products_id'], $cart->get_quantity(tep_get_uprid($HTTP_POST_VARS['products_id'], $attributes))+1, $attributes);
Thank You