PO is getting auto rejected.

A requisition has been created, one of the approver from the route list is end dated. So, when trying to approve the PO it is getting rejected. Is this the reason for the PO to get rejected. When we are trying to autocreate the PO from requisition in the lower instance, we are getting an 'invalid requisition number' error. When we are trying to run the reset program to approve the PO, the program is completing with Warning status. How to approve this PO, is there any way to approve it.