Populating Customer PO in Sales Invoice/Delivery Note Items Level


I am trying to populate Customer PO at Delivery/Invoice Line Item Level, i am following the instruction from privious discussion and not able to get the desired results … following is the configuration i have tried …

  1. Customized Delivery Note Item and Sales Invoice Item by creating a custom filed …
    Name: po_no
    Label: Customer’s Purchase Order No
  2. Reloaded the configuration.

With the above configuration, i’m able to get only blank field, but if the delete this configuration and create the link field using Sales Order, Auto Generated Sales Order Number is populating properly, also at the Delivery Note level Customer’s Purchase Order No is getting populated properly.

What am i missing here ?

Appreciate your help !

Have also tried the Custom Script suggest in “Customer PO number on invoice print format” thread by creating 2 new custom fields, but the same is not updating the required information in those fields !