Exception in simple program using opentk.openal

Question

Where the code initially came from

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using OpenTK;
using OpenTK.Audio.OpenAL;

namespace OpenTK_OpenAL
{
    class Program
    {
        static unsafe void Main(string[] args)
        {
            IntPtr device = Alc.OpenDevice(null);
            ContextHandle context = Alc.CreateContext(device, (int*)null);

            Alc.MakeContextCurrent(context);

            string version = AL.Get(ALGetString.Version);
            string vendor = AL.Get(ALGetString.Vendor);
            string renderer = AL.Get(ALGetString.Renderer);
            Console.WriteLine(version);
            Console.WriteLine(vendor);
            Console.WriteLine(renderer);
            Console.ReadKey();
        }
    }
}

I am looking at the link above and wrote a program, but the program does not work. Can I get a suggestion of why this doesn't work? There is an exception at the very beginning of the code, IntPtr device = Alc.OpenDevice(null);.