Error: System: Item000020 for schedule line 000040 is in the work area

Hi SAP Gurus,

I would like to ask your help in this issue.

Background: During Sales Order Change (VA02), If i did a change example change in quantity and then save, I am encountering this issue. However, when i try to change it again, I was able to change and save the sales order.

I am not sure where else to check since it's a bit weird. The issue is not happening in other sales area. This only happens in the new sales area we created.

But ABAP is saying that the issue is happening in a sap standard program.

Please advice.

Thanks.

Regards,

Erza