There are times when the journal's amount is higher than the bill it will be applied to, when we try to apply this to a bill, the system will show a message "Negative Payment is not Allowed" .
Here are the steps that you can follow to be able to apply and save the payment:
1. Open the Bill>Make Payment
2. Check/Mark first the journal to apply to the bill
3. Then change the amount on the Payment field to the same amount as the bill, put a negative sign.
4. Click Save