Loan calculator using while loop - vb.net

Question

I am creating a loan calculator and my loop keeps breaking. I got my stats correct, however I now need to move to a ListBox with more stats.
I can't get this while loop to work I have tried different ways with no avail. This is giving me a headache and I don't know what I am doing wrong.
Public Class Form1
Dim principleamount As Decimal
Dim numberofyears As Decimal
Dim interestrate As Decimal
Dim total As Decimal
Dim paymentnumber As Decimal
Dim currentbalance As Decimal
Dim interestfortheperiod As Decimal
Dim paymentamouhnt As Decimal
Dim newbalance As Decimal
Dim numberofpayments As Decimal
Dim payment As Decimal
Dim interestamount As Decimal
Dim numberofperiods As Integer
Private Sub btncalc_Click(sender As Object, e As EventArgs) Handles btncalc.Click
principleamount = txtprinciple.Text
numberofyears = txtyears.Text
'interest rate
If rba.Checked Then
interestrate = 1.035
End If
If rbb.Checked Then
interestrate = 1.04
End If
If rbc.Checked Then
interestrate = 1.65
End If
If rbc.Checked Then
interestrate = 1.08
End If
If rbd.Checked Then
interestrate = 1.08
End If
If rbe.Checked Then
interestrate = 0.1
End If
'monthly,weekly paymentplan
If rbmonthly.Checked Then
numberofpayments = numberofyears * 12
interestfortheperiod = interestrate / 12
End If
If rbweekly.Checked Then
numberofpayments = numberofyears * 26
interestfortheperiod = interestrate / 26
End If
payment = (principleamount * interestfortheperiod) / (1 - (1 + interestfortheperiod) ^ -numberofpayments)
txtpayment.Text = Format(payment, "#.00")
While principleamount >= 0
paymentnumber += 1
lbpaydetails.Items.Add("Payment Number: " & paymentnumber & " Current Balance: " & & "Interest for the Period: " & & "Payment Amount:" & & "new Balance:" & )
End While
End Sub
End Class

Answer 1

The while loop is going forever, so you need to find a way to decrease 'princlipleamount' in the loop. I am not entirely sure what the code does and how it behaves with your form, so i can not actually solve it.
P.S.
If you are trying to get 'numberofpayments' to be negative, don't put a dash in front of it like this:
payment = (principleamount * interestfortheperiod) / (1 - (1 + interestfortheperiod) ^ -numberofpayments))
But put it in Math.Abs() like this:
payment = (principleamount * interestfortheperiod) / (1 - (1 + interestfortheperiod) ^ Math.Abs(numberofpayments))
Also, you got a bracket missing at the end, i filled it in for you.
Good luck! ;)