[RESOLVED] Code that generates a mouse click event doesn't work

[gregorian]

This program is supposed to move to a button and click on it. When the button is clicked, it changes text.

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


namespace WindowsFormsApplication1
{
    public partial class Form1 : Form
    {
        [DllImport("user32.dll", CharSet = CharSet.Auto, CallingConvention = CallingConvention.StdCall)]
        public static extern void mouse_event(long dwFlags, long dx, long dy, long cButtons, long dwExtraInfo);

        private const int MOUSEEVENTF_LEFTDOWN = 0x02;
        private const int MOUSEEVENTF_LEFTUP = 0x04;
        private const int MOUSEEVENTF_RIGHTDOWN = 0x08;
        private const int MOUSEEVENTF_RIGHTUP = 0x10;

        public Form1()
        {
            InitializeComponent();
        }

        private void Form1_Load(object sender, EventArgs e)
        {
          //My button is about 150 units away from the top left corner
            Cursor.Position = new Point(this.Location.X + 150, this.Location.Y + 150);

            DoMouseClick();
        }
        public void DoMouseClick()
        {
            //Call the imported function with the cursor's current position
            int X = Cursor.Position.X;
            int Y = Cursor.Position.Y;
            mouse_event(MOUSEEVENTF_LEFTDOWN, X, Y, 0, 0);           
            mouse_event(MOUSEEVENTF_LEFTUP, X, Y, 0, 0);
        }

        private void button1_Click(object sender, EventArgs e)
        {
            button1.Text = "Clicked";
        }

    }
}

It moves till the button but it does not click on it. I don't know if something's wrong with the code or if I'm being blocked by some feature of Windows 7. Thank you for your help.