When we have the Purchase Order module unlocked, the PO field can only contain a PO number from a saved PO for that vendor.
- In the Open Invoice , click the binoculars button.
- Click Find Now in the new window to search for the saved purchase orders
- Highlight the correct Purchase Order and click Open.
- The PO number will show in the PO number box and we can now click save to successfully save the invoice.