C c deletion

When I delete a cost center, I am getting the following message.

<b>KS 266 Deletion not possible (usage is in table T811C)</b>

I created the cost center and then locked it for postings and then tried deleting it. It is still giving the above message in SAP 5.0.

I already implemented SAP note, 731762, but it still does not work

Can anyone clarify me as to where I should check to correct it.