PO Item Price lost after adding Return Item

Dear Experts,

Found a strange case as below -

Refer the following screen, price was already carried to the following PO Item 160 -

GR & IR were fully executed for this PO Item as below -

However, when adding a new PO Item 10010 as "Return" Item, found the following error for the above PO Item 160 after clicking "Check" button -

"

Net price must be greater than 0

Message no. 06218

Diagnosis

The net price is less than or equal to 0, but the invoice receipt (IR) indicator has been set.

Procedure

If you want to create a purchase order without a value, you must set the IR indicator to " ".

"

Then, the price had lost under "Item Details - Conditions" tab for both the Normal Item 160 & Return Item 10010 -

Only this PO Item 160 with Material no. 433-15862-980208 had such problem while there was no problem for other PO Item(s) with same status (fully GR & IR) & other Material no(s). when adding Return Item(s) for these PO Item(s).

Could you advise why the above price had lost and error (Message no. 06218) was found ? and How to avoid this problem with error (Message no. 06218) found ?

NOTE: Although the error can be fixed after manually inputting the price under the "Item Details - Conditions" tab, we had limited users to input price in this section (by adjusting authorization) so have to avoid this problem with error (Message no. 06218) found.

Many Thanks,

KH Fong