C#无法生成初始化向量IV

using System;
using System.Security.Cryptography;

class Program
{
    static void Main()
    {
        using (AesManaged aes = new AesManaged())
        {
            aes.GenerateIV();
            byte[] iv = aes.IV;
            Console.WriteLine("Initialization Vector (IV): " + Convert.ToBase64String(iv));
        }
    }
}

using System;
using System.Security.Cryptography;

class Program
{
    static void Main()
    {
        using (DESCryptoServiceProvider des = new DESCryptoServiceProvider())
        {
            des.GenerateIV();
            byte[] iv = des.IV;
            Console.WriteLine("Initialization Vector (IV): " + Convert.ToBase64String(iv));
        }
    }
}

using System;
using System.Security.Cryptography;

class Program
{
    static void Main()
    {
        using (TripleDESCryptoServiceProvider tripleDes = new TripleDESCryptoServiceProvider())
        {
            tripleDes.GenerateIV();
            byte[] iv = tripleDes.IV;
            Console.WriteLine("Initialization Vector (IV): " + Convert.ToBase64String(iv));
        }
    }
}