winform:窗体在panel里面打开后,怎样让窗体获得焦点

Panel2.BringToFront();
cabinetForm.BringToFront();
这代码没用;

           Frm_CardDetails CardDetails = new Frm_CardDetails();
            CardDetails.TopLevel = false;
            panel2.Controls.Add(CardDetails);
            panel2.Controls[0].Top = (panel2.Height - panel2.Controls[0].Height) / 2;
            panel2.Controls[0].Left = (panel2.Width - panel2.Controls[0].Width) / 2;
            CardDetails.Show();
这是我写的代码