Split Valuation

Hi,

I want to activate split valation for a material. There is no stock for this material. A purchase order already delivered and invoice also done. I am trying to change the details of MRP1,2 and Accounting details for this materials, I am getting an Error that a PO exists for this material, which actually got delivered and invoice done.

Is there any way to activate split valuation for this material other than deleting the PO & reversing the GR/IR for the respective PO.

Pls advice.

Regards,

Venu