private Form2 toll;
        private void button1_Click(object sender, EventArgs e)
 
            {
 
                if (toll == null)
                {
                   toll = new Form2();
 
                    toll.FormClosing += new FormClosingEventHandler( _
                      Form2_Closing);
 
                    toll.Owner = this;
 
                    // button1.Enabled = false;
 
                    toll.StartPosition = FormStartPosition.Manual;
                    toll.Location = new Point(this.Right, this.Bottom - _
                      toll.Height);
                    toll.Show();
                }
                else
                {
 
                    toll.Close; <-------- hier liegt mein Problem!
                }
            }