a Purchase Order is Not Selected to Create Voucher in Peoplesoft ?

Hi All,

A Purchase Order was created for $70,000.00 out of which $47,000 already have been invoiced. This PO is for service but was distributed by 'Quantity'. Final check box is checked and Comm. Control Close Flag is also checked in PO Distribution line. Do I need to change this PO line to 'Amount Only" But when I tried to change this PO's distribution line to 'Amount Only' I got message saying "An active voucher exists for the line(1). Cannot change Amount only flag. Cannot change Amount only flag once it is vouchered against. If you would still like to change the amount only flag, you need to delete/cancel those active vouchers for the PO line."