Cannot Create PO with generic article in IS-Retail

Hi all,

i am green in SAP Retail and meet some issues during creating PO. we are using generic article for all article master

When we try to create PO with reference PO from document overview in ME21N, it prompts the warning message "No subitems are copied when you copy a purchase order", then nothing happen, no data is copied.

Then we try to use ME21 to copy as reference, it can copy the PO but we cannot change to plant and document type during copying process.

(since we have to copy the PO from document type NB and change to STO document type UB so we need to change the plant, and doc. type.

Can anyone help me how to perform copy function in ME21N for generic articles ?

Thanks a lot!