我在将数据导入到asp.net页面时遇到问题，当我打开页面时，我发现所有文件都为空

 // this the code of the linked database with page 

        protected void Page_Load(object sender, EventArgs e)

    {

        if (String.IsNullOrEmpty(Request.QueryString["IDContent"]))

        {
            Response.Redirect("ContentList.aspx");
        }

        if (!String.IsNullOrEmpty(Request.QueryString["IDContent"]))
        {

            if (!IsPostBack)

//这是connectionString

            {
                SqlConnection Cn = new SqlConnection("Data Source = Lenovo;Initial Catalog = Web_Data; Integrated Security = True");
                Cn.Open();

                string Sql = "Select * From Content_Table Where IDContent = @IDContent";
                DataTable Dt = new DataTabel();
                SqlDataAdapter Da = new SqlDataAdapter(Sql, Cn);

                Da.SelectCommand.Parameters.AddWithValue("IDContent", Request.QueryString["IDContent"]);
                Da.Fill(Dt);
                Cn.Close();

//从Sql server导入数据的代码

                 if (Dt.Rows.Count > 0)

                {
                    TxtCategory2.SelectedValue = Dt.Rows[0]["FIDContent"].ToString();
                    TxtTitel2.Text = Dt.Rows[0]["ContentTitel"].ToString();
                    TxtDateTime2.Text = Dt.Rows[0]["ContentDateTime"].ToString();
                    TxtSummary2.Text = Dt.Rows[0]["ContentSummary"].ToString();
                    TextImage.Text = Dt.Rows[0]["ContentImage"].ToString();
                    TxtText2.Text = Dt.Rows[0]["ContentText"].ToString();

                    Image1.ImageUrl = TextImage.Text;

                }
                else
                {

                    LbMsg2.Text = " The Content is not exist!";
                }

                }

        }
    }