C# No areo in a drag-able form

See more:

C#

This is my code

Point lastClicked;
  private void Form1_MouseDown(object sender, MouseEventArgs e)
  {
      lastClicked = e.Location;
  }

  private void Form1_MouseUp(object sender, MouseEventArgs e)
  {

  }


  private void Form1_MouseMove(object sender, MouseEventArgs e)
  {
      if (e.Button == MouseButtons.Left)
      {
          this.Left += e.X - lastClicked.X;
          this.Top += e.Y - lastClicked.Y;
      }
  }

When I drag my form up the areo doesn't work in windows 7 with the from, and i would like it to do the areo on my drag-able form, plus can some please explain why it doesn't do the areo?

areo = when i drag the from up to the top of my screen the from maximizes