drag from listbox and drop to text two textboxes

this is form1
private void listBox1_MouseDown(object sender, MouseEventArgs e)
        {
            try
            {
                listBox1.DoDragDrop(listBox1.Items[listBox1.SelectedIndex].ToString(), DragDropEffects.Move);
            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.Message);
            }
        }

        private void txtBox1_DragEnter(object sender, DragEventArgs e)
        {
            try
            {
                if (e.Data.GetDataPresent(DataFormats.Text))
                {
                    e.Effect = DragDropEffects.Move;
                }
                else
                {
                    e.Effect = DragDropEffects.None;
                }
            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.Message);
            }
        }

        private void txtBox1_DragDrop(object sender, DragEventArgs e)
        {
            txtwpAM1.Text = System.Convert.ToString(e.Data.GetData(DataFormats.Text).ToString());
        }

private void button1_Click(object sender, EventArgs e)
        {
            _form.AddListBoxItem(textBox2.Text + "D"+ " "+textBox1.Text);

            this.Close();
        }