ORDER BY not working

cmd = new FbCommand("SELECT ISBN, BookNbr, Condn FROM tBooks WHERE Stat = 'For Sale'AND ISBN != '' AND DoNotReprice != 'T'  ORDER BY 'BookNbr' ASC", bookConn);
 
            try
            {
                if (bookConn.State == ConnectionState.Closed)
                    bookConn.Open();
 
                dr = cmd.ExecuteReader();
                int j = 0;
                while (dr.Read())  //  place all ISBNs in the array, starting pos -> 1 (0 is count)
                {
                    listISBNs[j].ISBN = dr.GetString(0);  //  ISBN
                    listISBNs[j].SKU = dr.GetString(1);  //  get SKU while we're here
                    listISBNs[j++].bookType = dr.GetString(2).ToString().ToLower().Contains("new") ? 'n' : 'u'; //  if condition is 'new'
                }
            }