This is realted to item numbering in billing doc.
Eg : - A sales order is created with line item no 10/20/30/40/50/60/70.When a billing doc is created the line item 60 of sales order is displyed as line item 100 and furher the line item 50 as 110 in the billing doc.
This happes only with item category which has a billing plan, the ones without the billing plan pick the right item number as in sales order into billing document.
i had checked the settings and in the copy controls the copy item number box is checked and also in VOFA the item number increment is set as 10
kIndly let me know as to how the same item number as in sales orders can be picked in billing document.