protected void btnAddComment_Click(object sender, EventArgs e)
        {
            if (string.IsNullOrEmpty(tbComment.Text))
            {
                lbResult.Text = "コメントを入力して下さい";
                return;
            }
            DataDoc dc = DataDoc.Instance(Server);

            lock (dc)
            {
                HttpCookie hc = Request.Cookies["user"];
                string     user;
                if (hc == null || string.IsNullOrEmpty(user = MasterPage.UserName(hc)))
                {
                    lbResult.Text = "ログインして下さい";
                    return;
                }
                Answer aw = dc.GetAnswer((int?)Session["Answer"]);
                if (aw == null)
                {
                    lbResult.Text = "対象がありません";
                    return;
                }
                dc.AddComment(aw.ID, user, tbComment.Text);
                dc.Save(null);
            }
            SetData();
        }