protected void Page_Init(object sender, EventArgs e)
 {
     if (!IsCallback && !IsPostBack)
     {
         Session.Remove("Letter");
         CreatePager();
     }
     if (Session["letter"] != null)
     {
         SqlDataSource1.SelectParameters[0].DefaultValue = String.Format("{0}%", ActivePageSymbol);
         DataViewAlphabet.DataBind();
     }
 }
 public void ChangeDataSource()
 {
     SqlDataSource1.SelectParameters[0].DefaultValue = String.Format("{0}%", ActivePageSymbol);
     DataViewAlphabet.DataBind();
 }