If You are doing Post & Print , or just Printing order confirmation, the this setup can come from 2 places:
Report selection - Purchases (check the appropriate selection that You are trying to print - invoice, order confirmation)
Or from Vendor card (that is used in this PO) --> Document Layouts.
There is a report 60007 assigned somewhere, but this report is no more in your system. Either extension has been removed, or report object has been changed to different number.