Inter Customer Transfer with in same Company code

Hi experts.

I am posting inter customer transaction Dr. one customer & Cr. another customer to transfer the Balance & to Make One customer balance should be zero.

I am using T-code f-30 document type DA. ( I enable the document type to allow inter company transaction)

then also I am getting error this

Consolidated companies ' ' and SEL are different

Diagnosis

The number of the affiliated company must be clear for the selected document type for all line items. In this case at least two different companies or a company in connection with a business partner who does not belong to a company are stated.

Procedure

If you selected the correct accounts, you must enter the document with a document type that allows cross-company posting. Otherwise, please correct the entered account.

Any body knows this solutions

Thanks

Ravi