
Down Payment Invoice must be based on Down Payment Request
You have created a down payment invoice not based on down payment request and chosen the Add button.
To base down payment invoice on down payment request:
Open the A/P or A/R Down Payment Invoice window and specify the code of the required business partner.
Choose the Copy From button, and click the option A/P or A/R Down Payment.
Choose the down payment to be the basis of the down payment invoice.