DI: Add Serialnumbers to AR Invoice Lines

Question

We are having a difficult time adding serialized items to AR invoices through the DI. It doesn't seem to be happy doing this no matter what we try. Probably a rookie mistake but I have tried several different ways of doing this with no luck. We get a 5002 error when trying to add the invoice if the serialized items are included on it. Works fine with just the non-serialized.
Here is the current iteration of the code. The DB lookups work fine and return the desired values. The exact same serialized items can manually be added to an invoice without any issues. If anyone can offer some advice I would  greatly appreciate it.
Thanks,
Matt
Dim EINV As SAPbobsCOM.Documents
Dim SerialNumber As SAPbobsCOM.SerialNumbers
Set EINV = Company.GetBusinessObject(oInvoices)
'Snip
'EINV setup and non-serialized items added
'No problems until we try adding serialized items
'All values return properly and can be added manually to an invoice.
'Fails with a 5002 when EINV.Add is invoked after serialized items are added.
'EINV.Add works fine with serialized code disabled.
If SerialRS.RecordCount > 0 Then
   SerialRS.MoveFirst
   Do While SerialRS.EOF = False
    STech = SerialRS.Fields("TechNumber").Value
    SItemID = SerialRS.Fields("ItemID").Value
    SSerial = SerialRS.Fields("Serial").Value
    If STech = TechNo Then
      EINV.Lines.Add
      EINV.Lines.SetCurrentLine (EINV.Lines.Count - 1)
      EINV.Lines.ItemCode = RTrim(SItemID)
      EINV.Lines.Quantity = 1
      EINV.Lines.TaxCode = "ZERO"
      EINV.Lines.WarehouseCode = TechNo
      Set SerialNumber = EINV.Lines.SerialNumbers
      SerialNumber.SetCurrentLine (SerialNumber.Count - 1)
      Set RecSet3 = Company.GetBusinessObject(BoRecordset)
      RecSet3.DoQuery ("select top 1 sysserial from osri where intrserial = '" & SSerial & "'")
                                                                                If RecSet3.RecordCount > 0 Then
          SerialNumber.InternalSerialNumber = SSerial
          SerialNumber.SystemSerialNumber = RecSet3.Fields("sysserial").Value
       End If
      End If
      SerialRS.MoveNext
    Loop
End if
Addresult = EINV.Add
If (Addresult <> 0) Then
  Call Company.GetLastError(nErr, errMsg)
  If (0 <> nErr) Then
     MsgBox ("Found error:" + Str(nErr) + "," + errMsg)
  End If
End If

Answer 1

This is evidently an issue with adding non-serialized items to an invoice before adding serialized items through the DI. It looks like the DI was trying to add the serialnumbers to the non-serialized doclines despite our best efforts to add them to the appropriate items. Once we changed the order of our code and added the serialized items first it worked just fine.
On a related note, if you add individual lines to an invoice for the same item (multiple lines of single quantity for the same item instead of a single line with a quantity > 1) the DI will only add serialnumbers to the first docline occurence of the item in question.