Hi,
The reason is that no valid payment method found.
please check below:
1) Do you maintain the payment method U in the vendor master? (You can indicate the payment method either in vendor master or on the invoice )
2) Do you indicate the house bank used for this payment method in FBZP (bank determination) ?
3) have maintained some required condtion for your payment method in (FBZP - payment method in country). For example, the payment method requires street ? bank account etc.
after the double check please delete the proposal and rerun again.