cant find duplicate doc

Why i cant find the duplicate documents at the view? while the
duplicate documents did show at the web.
Is the getNthDocument cause this problem?


Function getOutStandingAmt(paymentDb As notesDatabase, invoiceNo As
String, invoiceAmt As Double, invoiceExchangeRate As Double, invFee As
Double, invTax As Double, invOPE As Double) As Double
Const CONST_PAYVW = "($ByInvoiceNo)"

Dim paymentVw As notesView
Dim paymentDoc As notesDocument
Dim paymentCol As notesDocumentCollection

Dim paidFee As Double
Dim paidTax As Double
Dim paidOPE As Double

Dim convertedFee As Double
Dim convertedTax As Double
Dim convertedOPE As Double

Dim paymentAmt As Double
Dim convertedPaymentAmt As Double
Dim i As Integer

If Not GetView(paymentDb , CONST_PAYVW, paymentVw ) Then
getOutStandingAmt = Cdbl(invoiceAmt)
Exit Function
End If

Set paymentCol = paymentVw.getAllDocumentsByKey(invoiceNo, True)
If paymentCol.count = 0 Then
getOutStandingAmt = Cdbl(invoiceAmt)
feeAmt = invFee
opeAmt = invOPE
taxAmt = invTax
paidAmt = 0
Exit Function
End If

paymentAmt = 0
paidOPE = 0
paidFee = 0
paidTax = 0

For i = 1 To paymentCol.count
Set paymentDoc = paymentCol.getNthDocument(i)
convertedPaymentAmt = 0
convertedPaymentAmt = Cdbl(paymentDoc.PaymentAmount_tx(0)) *
Cdbl(invoiceExchangeRate)
Select Case paymentDoc.PaymentType_kw(0)
Case "OPE":
paidOPE = Cdbl(paidOPE) + (Cdbl(paymentDoc.PaymentAmount_tx(0)) *
Cdbl(invoiceExchangeRate))
Case "Fee":
paidFee = Cdbl(paidFee) + (Cdbl(paymentDoc.PaymentAmount_tx(0)) *
Cdbl(invoiceExchangeRate))
Case "Service Tax":
paidTax = Cdbl(paidTax) + (Cdbl(paymentDoc.PaymentAmount_tx(0)) *
Cdbl(invoiceExchangeRate))
End Select
paymentAmt = paymentAmt + convertedPaymentAmt
Next
paidAmt = Cdbl(paymentAmt)
feeAmt = Cdbl(invFee) - Cdbl(paidFee)
taxAmt = Cdbl(invTax) - Cdbl(paidTax)
OPEAmt = Cdbl(invOPE) - Cdbl(paidOPE)

getOutStandingAmt = Cdbl(invoiceAmt) - Cdbl(paymentAmt)
End Function