Error on creating Incoming Payment that links to another Incoming Payment

Question

Hi Experts,
I am trying to create an Incoming Payment to pay an Invoice, as well as to use another Incoming Payment with an open balance (with Payment On Account box checked) to offset part of this payment.
Conceptually...
Incoming Payment A (-$75)
   --- link to Invoice B   ($85)
   --- link to Incoming Payment C  (-$10)
This can be done manually, but by using DI API, I am facing this error:
"-10: Base document card and target document card do not match.  (RCT2.DocLine)(line: 2)"
Here is the source code:
Dim oPayments As Payments = DirectCast(oCompany.GetBusinessObject(BoObjectTypes.oIncomingPayments), Payments)
' [HEADER]
oPayments.CardCode = "C0001"
oPayments.DocDate = Today
oPayments.DocType = BoRcptTypes.rCustomer
oPayments.CashSum = 0
oPayments.BankChargeAmount = 0
oPayments.TransferAccount = "12180208"
oPayments.TransferDate = Today
oPayments.TransferSum = 75
oPayments.LocalCurrency = BoYesNoEnum.tYES
' [LINE 1 - AR Invoice B.]
oPayments.Invoices.InvoiceType = BoRcptInvTypes.it_Invoice
oPayments.Invoices.DocEntry = 16949
oPayments.Invoices.SumApplied = 85
' [LINE 2 - Incoming Payment C with Open Balance.]
oPayments.Invoices.Add()
oPayments.Invoices.InvoiceType = BoRcptInvTypes.it_Receipt
oPayments.Invoices.DocEntry = 20338           ' Journal Entry Number of the Incoming Payment
oPayments.Invoices.SumApplied = -10
If oPayments.Add() <> 0 Then
    oCompany.GetLastError(errCode, errMessage)
    BarError(String.Format("{0}: {1}", errCode, errMessage))
Else
    BarSuccess("Success.")
End If
Initially I tried to set
oPayments.Invoices.DocEntry
with the Incoming Payment's DocEntry, but after trial and error, I realized I should be using the Incoming Payment's Journal Entry's Number instead. So this field should be correct. (If I were to use the Incoming Payment's DocEntry for this field, I get the "-2028: No matching records found (ODBC -2028)" error.)
I have ensured that the Incoming Payment C's CardCode is the same as the one I set in
oPayments.CardCode
, so I'm not sure why it gives an error saying the document cards do not match. I would appreciate any form of help on this! Thanks!

Answer 1

Hi,
I am not trying to Pay to Account (you are referring to the top left radio button of the Incoming Payment right?). I am trying to create an Incoming Payment that uses another over-paid Incoming Payment (i.e. Open Balance > 0) to offset its Amount Due.
Anyway I have found the solution to my problem. It seems that I need to also set the
oPayments.Invoices.DocLine
value to the over-paid Incoming Payment's Journal Entry's document line which contains the same business partner as my Incoming Payments. This DocLine value is usually 1 (0-based), as SAP usually creates the Journal Entry with the BP row in the second row.