Intercompany sales process

Dear ALL SD Guru,

I am doing the intercompany sales process . For the same task i have created the sales order , delivery and finally create the invoice for the customer . After that when i am trying to create the intercompany invoice , system is showing me error " Sales organization is not defined" How ever i have done all the following required setting related to create the intercompany invoice in the system.

1- Assign the supplying company code sales area to deliverying plant.

2 Create one internal customer with supplying comany code and same sales area .

3 Assign internal customer to ordering sales organization

4 Assgn default intercompany billing document type (IV) to order type (OR)

5 I have extended the articles by supplying company code sales area

6 maintain the copy control in bet Or & IV

Is there any other setting required to execute this process , Please tell me

Waiting your response

Abhi