i'm creating a customized server control with modelpopupextender

hi all,

I have created a server control and included the control modelpopupextender.

but i can't make the modelpopupextender working the customize server control rendered at screen.

Is there any idea?

protected override void OnInit(EventArgs e)
        {
            base.OnInit(e);
            txt_obj.ID = this.ID + "textFillin";
            btn_obj.ID = this.ID + "buttonContrl";
            btn_ok.ID = this.ID + "OkButton";

            mp_popup.ID = this.ID + "popUp";
           // btn_obj.Click += new EventHandler(OnClickLookup);
            this.Controls.Add(txt_obj);
            this.Controls.Add(btn_obj);
            wc_container.Controls.Add(btn_ok);

            mp_popup.PopupControlID = wc_container.ID;
            mp_popup.TargetControlID = btn_obj.ID;
            mp_popup.OkControlID = btn_ok.ID;

            this.Controls.Add(mp_popup);
        }
        protected override void Render(HtmlTextWriter writer)
        {
            base.Render(writer);
            btn_obj.RenderControl(writer);
            txt_obj.RenderControl(writer);
            mp_popup.RenderControl(writer);
        }

Regards,

MH