Problem creating Form

Question

Hi everyone....
This is my problem

     public partial class Expedientes : UserControl
    {
        FormX AddNewForm = new FormX();

 private void button1_Click(object sender, EventArgs e)
{
AddNewForm.Show();
}

  private void button2_Click(object sender, EventArgs e)
{
AddNewForm.Close();
}
}

When I close the form and try to reopen it, this error occurs:
Can not access a disposed object.

How I solve can it?

Thanks people