不停报错，说小弟我的OnpaintBackground没有合适方法重写

不停报错，说我的OnpaintBackground没有合适方法重写.

        private void button1_Click(object sender, EventArgs e)
        {
            InvokePaintBackground();
            this.Hide();
            this.Visible = true();
        }


        protected override void OnpaintBackground(PaintEventArgs e)
        {
            int y, dy;
            y = this.ClientRectangle.Location.Y;
            dy = this.ClientRectangle.Height / 256;
            for (int i = 255; i >= 0; i--)
            {
                Color c = new Color();
                c = Color.FromArgb(Convert.ToInt32(textBox1.Text.ToString()), i, Convert.ToInt32(textBox2.Text.ToString()));
                SolidBrush sb = new SolidBrush(c);
                Pen p = new Pen(sb, 1);
                e.Graphics.DrawRectangle(p, this.ClientRectangle.X, y, this.Width, y + dy);
                y = y + dy;
            }

        }

        private void Form1_BackgroundImageChanged(object sender, EventArgs e)
        {

        }
    }
}
错误提示：
错误 1 “WindowsFormsApplication6.Form1.OnpaintBackground(System.Windows.Forms.PaintEventArgs)”: 没有找到适合的方法来重写 C:\Users\Administrator\Desktop\编程错误代码\WindowsFormsApplication6\WindowsFormsApplication6\Form1.cs 27 33 WindowsFormsApplication6

------解决方案--------------------
C#,发到C#那问问吧。