Shipment by Weight

When you use commerce server 2007, you can calculate shipment by 3 ways:
1. Shipment by Total
2. Shipment by Quantity
3. Shipment by Weight.

If you tried to use shipment by weight you will face problem because weight is not default property of products.
You need to define weight property and add it to products needs shipment by weight.
if you run total pipeline against basket and you have item hasn't weight property and you assigned shaipment by weight to it, you will find error:
Not found: orderform.items (0). _product_weight. This shipping method requires that all products in the catalog define weight.

This error occurs if:
1. you didn't have weight property of product definition.
2. You didn't fill it's value(null).
3. you didn't add correct information about product (CatalogName, ProductId, VariantId).
4. You didn't run basket pipeline before run total pipeline.