OpenChild From Thro MdiForm Open

 private Form activeForm = null;
        private void OpenChildForm(Form childForm)
        {
            if (activeForm != null)
                activeForm.Close();
            activeForm = childForm;
            childForm.TopLevel = false;
            childForm.FormBorderStyle = FormBorderStyle.None;
            childForm.Dock = DockStyle.Fill;
            panelChildForm.Controls.Add(childForm);
            panelChildForm.Tag = childForm;
            panelChildForm.AutoScroll = true;

            childForm.BringToFront();
            childForm.Show();
        }

 private void BtnOpenModuel_Click(object sender, EventArgs e)
        {
            
            string str = !this.rbtnMorning.Checked ? (!this.rbtnEvening.Checked ? (!this.rbtnMeeting.Checked ? "Special" : "Meeting") : "Evening") : "Morning"; 
            new Attendance { sShift = str }.Show();

        }

line number 4  user mdiForm Options