Revenue Postings on profit center

Hi All

I am trying to post a GL account which is maintained as cost element category 11. I have assigned a profit center during the posting, but i get the error that this account requires a CO object. Mesg No.KI235.

I feel that GL accounts with cost element cat.11 can be posted on a profit center without a CO object.

Is there any note that I need to apply. We are using SAP ECC 6.0 Release 603 Level 002.

Regards

Ram