opening modal popup extender from .cs file

DataListItem row = (DataListItem)(((ImageButton)e.CommandSource).NamingContainer);
           ImageButton ImageButton = (ImageButton)DataList1.Items[row.ItemIndex].FindControl("Image1") as ImageButton;
           Label lblnum = (Label)DataList1.Items[row.ItemIndex].FindControl("lblnum") as Label;
           AjaxControlToolkit.ModalPopupExtender modpopup = new AjaxControlToolkit.ModalPopupExtender();
           modpopup.TargetControlID = "ImageButton";
           modpopup.PopupControlID = "pnlDirImages";
           modpopup.BackgroundCssClass = "modalBackground";
           modpopup.CancelControlID = "btnclose";
           conn.Open();
           string strquery = "some query";
           SqlDataAdapter da = new SqlDataAdapter(strquery, conn);
           da.Fill(objds);
           conn.Close();
           if (objds.Tables[0].Rows.Count > 0)
           {
               dlImages.DataSource = objds.Tables[0];
               dlImages.DataBind();
               pnlDirImages.Visible = true;
               modpopup.Show();
           }
           else
           {
               pnlDirImages.Visible = false;

           }