Unable to close the CST-period of July

There is a new ORG which is created in April .Due to user negligence, there was no corresponding cost accounting organization associated with this ORG until yesterday(8,August).

Yesterday, user associated this ORG with a cost accounting organization and encountered an error when running the PAC program（Launch Periodic Cost Processer）.

According to the error message, there is a PO return whose associated PO Receipt cannot be found.The PO Receipt is created in June,the PO Return is create in July.

Now，because of the error ,accountant can't close the CST-Period of July.

Please help with this problem,thanks!