Adding a list to an object

I've created a shopping cart where products can be placed in. Inside the shoppingcart there is one button to add all of the products inside an order.

When the "Bestellen" button is clicked the following microflow will be called:

The new object "bestelling" is created but the products are not placed in the bestel_lines table. Inside the loop this is filled in the bestel_lines table:

I can't seem to figure out why the products are not placed in the bestel_lines table. Thanks in advance for helping me out.