title: Generic.List of Bitmaps cant add a new Bitmap
body: <p>Can't add New Bitmap due NullReferenceException. What is the cause of this?</p>
  
  <pre><code>Dim bitmap As Bitmap = New Bitmap(10, 10)
  Dim listbitmap As List(Of Bitmap)
  Dim rand As Random
  
  Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
      For x As Integer = 0 To 9
          For y As Integer = 0 To 9
              bitmap.SetPixel(x, y, Color.Black)
          Next y
      Next x
      PictureBox1.Image = bitmap
      Me.Refresh()
      listbitmap.Add(New Bitmap(bitmap)) 'error starts here
  End Sub
  </code></pre>