Array.Sort() function

Can someone tell me why I'm getting the following error?  "The type or namespace name 'Sort' does not exist in the namespace 'Array'"

I'm using VS 2012 on Windows 8.1. 

using System;
using System.Collections;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace Arrays
{
    class Program
    {
        public static void Main(string[] args)
        {
            //var items = new Item[5];
            //Random r = new Random();
            //for (int i = 0; i < items.Length; i++)
            //{
            //    items[i] = new Item(r.Next());
            //}

            //Console.WriteLine("Items: ");
            //foreach (Item item in items)
            //{
            //    Console.WriteLine("ItemID = {0}", item.ID);
            //}

            var Authors = new String[5];
            Authors[0] = "Faulkner";
            Authors[1] = "Proust";
            Authors[2] = "Stephenson";
            Authors[3] = "Gibson";
            Authors[4] = "Melville";

            Console.WriteLine("Authors...");
            foreach (string s in Authors)
            {
                Console.WriteLine(s);
            }

            Array.Sort( Authors );

            Console.WriteLine("Authors...");
            foreach (string s in Authors)
            {
                Console.WriteLine(s);
            }




        }
    }
}