A valid $0 payment amount may exist if an invoice was received, recorded in Medline's system but then backed out. If the invoice was never reposted, it may appear as a $0 payment amount:
- Invoice was 'paid' with a full shortage
- Invoice received with no supporting documentation
- Invoice received but not on latest statement
- Invoice received but AP was asked not to pay
- Invoice received but cleared against a credit
Please create a ticket to work with an AP rep to resolve if you disagree with the $0 payment amount.
Also, you can try the tips found in the article "Common Input Errors"