.vb keeps giving 0 as total amount you need to pay - vb.net

Question

So i had to make a program where you can buy stuff when clicking on the buttons, when the amount totals more than 1k you can roll for a discount. This all goes well until I have to use a label to indicate the total amount you need to pay minus the discount. This label keeps staying 0, no matter what. Could anyone help?
Form1 for the "shop":
Public Class Form1
Dim i As Integer = 1
Dim totaalbedrag As Double
Public Sub Actie()
If Val(TextBox3.Text) > 1000 And i = 1 Then
If MsgBox("Wil je strijden voor korting? Zo niet zal deze pop-up niet meer komen dus maak je keuze!", vbYesNo) = vbYes Then
Me.Hide()
Form2.Show()
Else
i = 0
End If
End If
End Sub
Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
Label6.Text = Val(Label6.Text) + 1
TextBox1.Text = Val(TextBox1.Text) + 250
TextBox3.Text = Val(TextBox1.Text) + Val(TextBox2.Text)
Actie()
End Sub
Private Sub Button2_Click(sender As Object, e As EventArgs) Handles Button2.Click
Label7.Text = Val(Label7.Text) + 1
TextBox2.Text = Val(TextBox2.Text) + 300
TextBox3.Text = Val(TextBox1.Text) + Val(TextBox2.Text)
Actie()
End Sub
Private Sub Timer1_Tick(sender As Object, e As EventArgs) Handles Timer1.Tick
TextBox4.Text = korting & " procent"
totaalbedrag = totaalbedrag - totaalbedrag * korting / 100
TextBox5.Text = Val(totaalbedrag)
End Sub
Private Sub Button3_Click(sender As Object, e As EventArgs) Handles Button3.Click
MsgBox("Gefeliciteerd met de aankoop van totaal " & totaalbedrag & " euro!!", vbCritical)
End
End Sub
End Class
Form2 for the gambling:
Public Class Form2
Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
korting = Label1.Text
MsgBox("Gefeliciteerd, je hebt " & korting & " procent korting gekregen!", vbCritical)
Me.Hide()
Form1.Show()
End Sub
Private Sub Timer1_Tick(sender As Object, e As EventArgs) Handles Timer1.Tick
Label1.Text = Int(Rnd() * 10)
End Sub
End Class
Module to have a value as a public one:
Module Module1
Public korting As Integer = 0
End Module
You basically should pay attention to this code of line since I think this is where all goes wrong:
Private Sub Timer1_Tick(sender As Object, e As EventArgs) Handles Timer1.Tick
TextBox4.Text = korting & " procent"
totaalbedrag = totaalbedrag - totaalbedrag * korting / 100
TextBox5.Text = Val(totaalbedrag)
End Sub

Answer 1

I am not at all sure of the timer event in Form1. Every time it ticks the discount is reapplied. If the program runs long enouth totaalbedrag will be very small.
I used .ToString("C") or "c" to display the result as currency. Some of displays are probably not currency. Change to the appropriate format string. https://learn.microsoft.com/en-us/dotnet/standard/base-types/standard-numeric-format-strings
For Random numbers please switch to the .net Random class.
Public Class Form1
Dim i As Integer = 1
Dim totaalbedrag As Decimal
Public Sub Actie()
Dim tb3Dec As Decimal
If Decimal.TryParse(TextBox3.Text, tb3Dec) AndAlso tb3Dec > 1000 AndAlso i = 1 Then
If MsgBox("Do you want to compete for a discount? If not, this pop-up will not come again so make your choice!", vbYesNo) = vbYes Then
Me.Hide()
Form2.Show()
Else
i = 0
End If
End If
End Sub
Private Sub Timer1_Tick(sender As Object, e As EventArgs) Handles Timer1.Tick
TextBox4.Text = korting & " procent"
totaalbedrag = totaalbedrag - totaalbedrag * korting / 100
TextBox5.Text = totaalbedrag.ToString("C")
End Sub
Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
Dim tb1Dec As Decimal
If Not Decimal.TryParse(TextBox1.Text, tb1Dec) Then
MessageBox.Show("Please enter a valid number in TextBox1.")
Exit Sub
End If
Dim tb2Dec As Decimal
If Not Decimal.TryParse(TextBox2.Text, tb2Dec) Then
MessageBox.Show("Please enter a valid number in TextBox2")
Exit Sub
End If
Label6.Text = (CDec(Label6.Text) + 1).ToString
TextBox3.Text = (tb1Dec + tb2Dec).ToString("c")
TextBox1.Text = (tb1Dec + 250).ToString("C")
Actie()
End Sub
Private Sub Button2_Click(sender As Object, e As EventArgs) Handles Button2.Click
Label7.Text = (CDec(Label7.Text) + 1).ToString("c")
Dim tb2Dec As Decimal
If Not Decimal.TryParse(TextBox2.Text, tb2Dec) Then
MessageBox.Show("Please enter a valid number in TextBox2")
Exit Sub
End If
Dim tb1Dec As Decimal
If Not Decimal.TryParse(TextBox1.Text, tb1Dec) Then
MessageBox.Show("Please enter a valid number in TextBox1")
Exit Sub
End If
TextBox2.Text = (tb2Dec + 300).ToString("C")
TextBox3.Text = (tb1Dec + tb2Dec).ToString("C")
Actie()
End Sub
Private Sub Button3_Click(sender As Object, e As EventArgs) Handles Button3.Click
MsgBox("Gefeliciteerd met de aankoop van totaal " & totaalbedrag & " euro!!", vbCritical)
End
End Sub
End Class
Public Class Form2
Private rand As New Random
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
korting = CInt(Label1.Text)
MsgBox("Gefeliciteerd, je hebt " & korting & " procent korting gekregen!", vbCritical)
Me.Hide()
Form1.Show()
End Sub
Private Sub Timer1_Tick(sender As Object, e As EventArgs) Handles Timer1.Tick
Label1.Text = rand.Next(0, 101).ToString 'returns an integer 0 to 100
End Sub
End Class
This fixes the Option Strict violations but I have no idea it this works for you. Let us know which label is showing 0.