Исчезает рисунок при прорисовке формы

    Private Sub btnPaint_Click(sender As System.Object, e As System.EventArgs) Handles btnPaint.Click
        Dim redPen As New Pen(Color.Red, 1)
        picMain.CreateGraphics.DrawEllipse(redPen, 1, 1, 100, 50)
    End Sub

    Private Sub PictureBox1_Paint(ByVal sender As Object, ByVal e As System.Windows.Forms.PaintEventArgs) Handles PictureBox1.Paint
        Dim redPen As New Pen(Color.Red, 1)
        e.Graphics.DrawEllipse(redPen, 1, 1, 100, 50)
    End Sub

  Private Sub PictureBox1_Paint(ByVal sender As Object, ByVal e As System.Windows.Forms.PaintEventArgs) Handles PictureBox1.Paint
        Dim redPen As New Pen(Color.Red, 1)
        e.Graphics.DrawEllipse(redPen, 1, 1, 100, 50)
    End Sub

    Private Sub picMain_Paint(ByVal sender As Object, ByVal e As System.Windows.Forms.PaintEventArgs) Handles picMain.Paint
        picMain.Image = Nothing 'Блокирует таймер
        Dim redPen As New Pen(Color.Red, 1)
        e.Graphics.DrawEllipse(redPen, 1, 1, 100, 50)
    End Sub
 
    Private Sub Timer1_Tick(sender As System.Object, e As System.EventArgs) Handles Timer1.Tick
        lblTimeNow.Text = CStr(TimeOfDay)
    End Sub

picMain.Image = Nothing

PictureBox1.Refresh

    picMain.Image = Nothing

picMain.Image = Nothing

picMain.Image = Nothing

        Dim BM As New Bitmap(PictureBox1.Width, PictureBox1.Height)
        Dim G As Graphics = Graphics.FromImage(BM)
        Dim redPen As New Pen(Color.Red, 1)
        G.DrawEllipse(redPen, 1, 1, 100, 50)
        PictureBox1.Image = BM