I am having trouble with a function in vb can anyone give me a suggestion?

Question

I am trying to calculate a cable bill of a residential customer and a business customer, when the customer checks the list box of the channels and the connections I need it to add it up. I have edited the code. Does my logic make sense?
for residential customers it is 4.50 processing,30 basic service and 5 per channel
so is the logic processing+basicservice *premium
Public Class Main
Private Sub btnCalculate_Click(sender As Object, e As EventArgs) Handles btnCalculate.Click
If Data_Validated_ok() = False Then Exit Sub
Dim premiumChannels As Integer = lstPremium.SelectedIndex
Dim Connections As Integer = lstConnections.SelectedIndex
Dim totalDue As Decimal
If radResidential.Checked Then
totalDue = CalcResidentialTotalDue(premiumChannels, Connections)
lblTotal.Text = totalDue.ToString("C2")
Else
totalDue = CalcBusinesssTotalDue(premiumChannels, Connections)
lblTotal.Text = totalDue.ToString("C2")
End If
End Sub
' make a function to calculate residential customers
Private Function CalcResidentialTotalDue(ByVal premiumChannels As Decimal, ByVal connections As Decimal
) As Decimal
Const ResidentialProcessing As Decimal = 4.5D
Const ResidentialBasic As Integer = 30
Const ResidentialPremium As Integer = 5
Return ResidentialProcessing + ResidentialBasic + ResidentialPremium * premiumChannels
End Function
' make a function to calculate business customers
Private Function CalcBusinesssTotalDue(ByVal premiumChannels As Decimal, ByVal connections As Decimal
) As Decimal
Const BusinessProcessing As Decimal = CDec(16.5)
Const BusinessBasic As Integer = 80
Const BusinessPremiumchannels As Integer = 50
Return BusinessProcessing + BusinessBasic + BusinessPremiumchannels * premiumChannels
End Function
here is  a pic of my listboxes
[IMG]http://i57.tinypic.com/muepug.png[/IMG]
http://i57.tinypic.com/muepug.png

Answer 1

The statement below is wrong in both functions.  You are passing the variable "connections" in the function parameter list and not using the variable.  I thing in the statement below you need to change connections to something else.
connections = Convert.ToDecimal(lstConnections.SelectedItem)
Here are the two parameter lists
1)    Private
Function calcResidentialTotal(ByVal connections
As Decimal,
ByVal premium As
Decimal)
As Decimal
2)   Private
Function calcBusinessTotal(ByVal connections
As Decimal,
ByVal premium As
Decimal)
As Decimal
jdweng