variable resets after initialized

hi guys,
i have a web form where I declare a list in the top of the class, the problem is that when I load the form, it resets the variable that I declared, after the page_load event fires




public partial class NewEditItemBook : System.Web.UI.Page
    {

        List<TitleAuthor> titleAuth = new List<TitleAuthor>();


        protected void Page_Load(object sender, EventArgs e)
        {
            if (!IsPostBack)
            {


                    B_TitleAuthor b = new B_TitleAuthor();

         & ...