Collision in C#

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;

namespace PBCollide
{
    public partial class Form1 : Form
    {
        Rectangle pb1;
        Rectangle pb2;

        public Form1()
        {
            InitializeComponent();
            pictureBox2.LocationChanged += new EventHandler(pictureBox2_LocationChanged);

        }

        void pictureBox2_LocationChanged(object sender, EventArgs e)
        {
            if (pb1.IntersectsWith(pb2))
            {
                MessageBox.Show("test");
            }
        }

        private void button4_Click(object sender, EventArgs e)
        {
            Point newloc = pictureBox2.Location;
            newloc.X -= 10;
            pictureBox2.Location = newloc;
        }

        private void timer1_Tick(object sender, EventArgs e)
        {
            pb1 = new Rectangle(pictureBox1.Location, pictureBox1.Size);
            pb2 = new Rectangle(pictureBox2.Location, pictureBox2.Size);
        }


    }
}