Sales order settlement to cost centre

Hi all

We have COPA activated for our client and normally all sales order are settled to COPA. Now for a free goods / sample issue scenario i want the sales order to be settled to cost centre

Is this possible?

I tried to create a settlement rule with settlement optional to cost centre alone and made the default object as cost centre. But i get a error PSG not defined?

Where am i wrong?

Please help

Thanks