delivery charge logic bug

Hi I have found a bug in the calculation of delivery.

I have 4 test products:
Product 1 - chargeable product
Product 2 - chargeable product
Product 3 - free delivery
Product 4 - collect in store only (so excluded from delivery cost)

I been testing different combinations of basket and looking at the calculations which I post to page.
The delivery cost is based on total weight and total size (width x height x depth)
The calculations for total weight and total size are correct
Testing for all 4 products in basket works out correct delivery charge.
Testing for Product 1 + Product 2 in basket works out correct delivery charge.
Testing Product 3 + Product 4 in basket fails as the delivery charge is calculated at the minimum delivery cost in my database.

So I wonder what could be the cause of this?

Originally I had in my eCart Merchandising Rule: AND SubTotal of ChargeDelivery ==1 (see screenshot) but having this is the rule failed the test for Product 1 + Product 2 in the basket - (but correctly calculate Product 3 + Product 4 being free delivery) So it seems that fixing the issue by removing the rule causes the 2 free delivery products from being free delivery.

I assume its my eCart Merchandising Rules?

I have attached screenshots of the eCart object in case you see anything obvious there that's a mistake?

Also attaching the php file that calculates the delivery (its a pass through file from my checkout address page to the payment page.

Chris

Subtotal of chargedelivery = 1 in your shipping rule seems odd. That would only be true if 1 and only 1 item in the cart has a delivery charge.