region对象1.union(region对象1);怎么不能实现

Question

我的代码错在哪里了
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Drawing.Drawing2D;
using System.Text;
using System.Windows.Forms;namespace WindowsApplication1
{
    public partial class Form6_Region类 : Form
    {
        public Form6_Region类()
        {
            InitializeComponent();
        }        private void Form6_Region类_Paint(object sender, PaintEventArgs e)
        {
        }
        protected override void OnPaint(PaintEventArgs e)
        {
            base.OnPaint(e);
            Graphics g = e.Graphics;
            Rectangle rect1=new Rectangle(10,10,100,100);
            Rectangle rect2=new Rectangle(40,3,100,100);
            Region reg1 = new Region(rect1);
            Region reg2 = new Region(rect2);
            g.FillRegion(new SolidBrush(Color.Red),reg1);
            g.FillRegion(new SolidBrush(Color.Yellow), reg2);
            reg1.Intersect(reg2);
        }
    }
}