Selenium Nunit addin install exception

I don't have enough rep to comment, so I am posting a question here. I read this question Get list of failing tests from Nunit. I am trying to implement the nunit addin, I used this code:

using System;
using System.Collections.Generic;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using NUnit.Framework;
using NUnit.Core.Extensibility;

namespace NunitAddin
{
    [NUnitAddinAttribute(Type = ExtensionType.Core,
       Name = "addin",
       Description = "addin")]
    public class NunitAddin : IAddin
    {
        public bool Install(IExtensionHost host)
        {
            IExtensionPoint listeners = host.GetExtensionPoint("EventListeners");
            if (listeners == null)
                return false;

            listeners.Install(this);
            return true;
        }
        public void TestStarted(NUnit.Core.TestName testName)
        {
        }

        public void TestFinished(NUnit.Core.TestResult result)
        {

        }
        public void RunStarted(NUnit.Core.TestName testName)
        {
        }

        public void RunFinished(NUnit.Core.TestResult result)
        {
        }

        public void UnhandledException(Exception exception)
        {
        }

        public void TestOutput(NUnit.Core.TestOutput testOutput)
        {
        }


    }
}

But when I call it using

var addin = new NunitAddin.NunitAddin();

var a = addin.Install(CoreExtensions.Host);

I get an error

NunitAddin.NunitAddin is not {0} extension point

on

 listeners.Install(this);

Does anyone know how to solve this problem?