Reg:- Need to create PO for Previous Period.

Dear All,
Can any one suggest me Is it possible to create Purchase order for Previous Period.

Now we are In APR-2013 We forget to create 1 Purchase order which is related to PMar-2012.

My Mar-2012 Period is still open. But while going create PO system automatically taking Creation date as today's date.

How can we create PO for 30-Mar-2012.
we are in R12.

Thanks in advance.....



Regards,
Narendra.