CO object in FB01

Hi FI/CO ers,

I am a abapper, and i m trying to create a BDC. For the data to be present in the BSID table ( Which is necessary for my BDC to work ), I tried posting a document through the transaction FB01, : --

Following are the details that I m providing.

In the first screen i give the company code as 0087, the document type as "RV" .

For the line items

1st posting key as 40 , account no as N09121,

but in the second screen the business area field is mandatory i am getting a error message like " Account N09121 requires an assignment to a CO object" when i provide the business area as 7034, can anybody tell me from where i am supposed to get the data that is to be given in this field ( Order) , if the data in context is not present then how to create it?

Please Explain....

Regards

Naren Rathinavelu