Child table value not flowing to webform

i created a webform of the “Sales Order” doctype and have added the “items” child table. The “Items” table has 4 fields: item code, quantity, valuation rate (read only) and amount (read only).
I can safely put the item code and quantity in the webform, but the rate value is not flowing to the web form.
Once i create an order however, i can see the rates and amount in the sales order.
Any idea, why it’s not visible in the webform? I want the customer to see the rates too once he selects an item.
There’s no customized doctype, all are default.

It’s not worked in the web form, you have to apply the logic using the web form script but it is tricky to develop.

ok. Thanks