Как преобразовать текст в целое число?

' Create coordinates of Line 
    Dim x As Integer = 250
    Dim y As Integer = 50
    Dim change As Integer = 0
    
      Private Sub picIO_Paint(ByVal sender As System.Object, ByVal e As System.Windows.Forms.PaintEventArgs) Handles picIO.Paint
 
        Dim g As Graphics = e.Graphics
 
        change = Convert.ToInt32(txtValue.Text) ' здес я я получаю следующее сообщение:Input string was not in a correct format.
        change = Integer.Parse(txtValue.Text)
 
        g.DrawLine(Pen, x, y - change, Width - 600, Height + change)
    End Sub

Public Event MyEvent(ByVal sender As Object, ByVal ValueToReturn As Integer)
    Private Sub TrackBar1_Scroll(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles TrackBar1.Scroll
 
        txtAGCO.Text = System.Math.Round(TrackBar1.Value)
        RaiseEvent MyEvent(Me, TrackBar1.Value)
    End Sub

 Private Sub Form3_MyEvent() Handles form3.MyEvent
        Dim change As Integer = 0
        change = form3.TrackBar1.Value * 10
        txtValue.Text = form3.TrackBar1.Value
       'Если добавить следующий  код, я могу использовать значения TrackBar1:
 Dim Pen As New Pen(Color.Black, 3)
Dim g As Graphics = picIO.CreateGraphics
        g.DrawLine(Pen, x, y - change, Width - 1500, Height + change)
    End Sub

Private Sub Form3_MyEvent() Handles form3.MyEvent
End Sub