Customer invoice error ..FB01

Hi Experts,

I am working on ECC 6.0, i am trying to post a customer invoice with T-Code FB01..

when i am trying to simulate this entry, system showing an error message, Account 800000 (revenue account) requies an assignment to CO object.

As i understand ,i need to assign one CO object to this revenue account (800000) .

but i dont know where to assign this..... Can any one tell me where to assign this any path or Tcode

Thanks in advance

Jerry