Cost Centre Derivation Issue at the time of PGI

Dear Experts,

At the time of Posting Post Goods Issue, SD Consultant is facing error that GL Account 6* requires assignment to a CO Object. According to my understanding, system should derive Cost Centre at the time of P.G.I through following logic : I have assigned Profit Centre : 999999 to the Cost Centre : ABCD and the said profit centre is being used at the time of Sales Order Posting. While doing PGI, system should derive cost centre data from Profit Centre Data which is used in Sales Order but currently system is not behaving like this. Another way is to assign respective cost centres against COGS Gls through T-Code : OKB9 which is not right I think. Because how can we map Cost Centre Data with Profit Centre Data in order to get Profit Centre Wise Profitability Reports? Please guide me any solution. Regards, Sapna