网格视图未显示结果

DataSource

DropDownList

GridView

    public partial class index : System.Web.UI.Page
    {
        SqlConnection conn = new SqlConnection();
        string option = \"\";
        protected void Page_Load(object sender, EventArgs e)
        {
            option = selectProductdropdown.SelectedValue;
        }

        protected void Button1_Click(object sender, EventArgs e)
        {
            Label2.Text = option;
            if (option == \"Books\")
            {

                Label3.Text = option;
                conn.ConnectionString = ConfigurationManager.ConnectionStrings[\"booksconnectionstring\"].ConnectionString;
                conn.Open();
                SqlCommand cmd = new SqlCommand(\"SELECT * from books\", conn);
                cmd.CommandType = CommandType.Text;

                SqlDataAdapter reader = new SqlDataAdapter(cmd);

                DataSet s = new DataSet();
                reader.Fill(s);
                GridView1.DataSource = s;
                GridView1.DataBind();
                conn.Close();
            }