
The down payment is already drawn to a document
You have tried to create an invoice. You have chosen the Total Down Payment button.
In the Down Payments to Draw window, you have selected a down payment request, but by the time you have chosen the OK button, another user drawn this down payment request into another target document.
You cannot draw down payment requests that were drawn into down payment invoices into invoice. Close the Down Payments to Draw window and open it again to view the updated list of down payments available to draw.