prepayment sales invoice anad final invoice

Hello I have three order with three invoice of the first two invoice is superior a quantity invoiced the third invoice is lower of the quantity invoicee then I just create final invoice I call aa all the deliveries of three orders of same customers The system blocks me with this message

tHE TOTAL PREPMT AMT TO DEDUCT CANNOT BE MORE THAN [number] ,..... debuger posted in codunit 80