VS 2012 Drawing in GroupBox via Sub

This works when it's clicked:
Private Sub GroupBox1_MouseDown(sender As Object, e As MouseEventArgs) Handles GroupBox1.MouseDown
Dim gr As Graphics = GroupBox1.CreateGraphics
gr.FillEllipse(Brushes.Green, 210, 25, 8, 8)
gr.Dispose()
End Sub

However during Form load
Public Sub New()
GreenLight()
End Sub
Sub GreenLight()
Dim gr As Graphics = Me.GroupBox1.CreateGraphics
gr.FillEllipse(Brushes.Green, 210, 25, 8, 8)
gr.Dispose()
End Sub
Nothing happens. What am I doing wrong, please???
Thanks in advance