Problem in creating third party PO

Question

I have tried to ceate the PO as suggested in earlier post by using the method of Shopping cart type icon on item details tab . This I have done for the consolidation . But as my PO has account assignment I entered the Cost Center . But system gives following message
Requisition 10000036, item 00010, assigned to other order account
Message no. 06251
I just exp[lain the scenario as follows
Iam simulating the Third Party Process and PRs are getiing generated in background at the time of Sales Order creation there are 2 sales order as follows
SO1
Mat1 10 Pcs Requisitioner R1
Mat2 15 Pcs R1
SO2
Mat1 20 Pc R2
PRs
PR1
Mat1 10 Pcs Requisitioner R1
Mat2 15 Pcs R1
PR2
Mat1 20 Pc R2
In PO
line Item 10 Mat1 30 Pc Del Sch Tab 10 & 20 Pc from R1 & R2
Line item 20 Mat2 15Pcs
Account assignment is same in all the PRs items and for PO also
And system gives error message
I hope you understand my problem

Answer 1

In third party process SO / PR / PO should be in integrity. Your manual modification violates this I think (you are making one PO item from two SO item...).
http://help.sap.com/erp2005_ehp_04/helpdata/EN/dd/560287545a11d1a7020000e829fd11/frameset.htm
Processing Third-Party Orders in Purchasing
When you save a sales order that contains one or more third-party items, the system automatically creates a purchase requisition in Purchasing. Each third-party item in a sales order automatically generates a corresponding purchase requisition item. During creation of the requisition, the system automatically determines a vendor for each requisition item. If a sales order item has more than one schedule line, the system creates a purchase requisition item for each schedule line.
Purchase orders are created from purchase requisitions in the usual way. For more information about creating purchase orders, see the Purchasing documentation. During creation of the purchase order, the system automatically copies the delivery address of your customer from the corresponding sales order. In a sales order, you can enter purchase order texts for each third-party item. When you create the corresponding purchase order, the texts are automatically copied into the purchase order. The number of the purchase order appears in the document flow information of the sales order.
All changes made in the purchase order are automatically made in the sales order as well. For example, if the vendor confirms quantities and delivery dates different from those you request and enters them in the purchase order, the revised data is automatically copied into the sales order.
Regards,
Csaba