Dynamically load DLL in .NET

InstanceThing.cs

//This is in LibFunctions.dll
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace LibFunctions
{
    public class InstanceThing
    {
        public int Sum(int a, int b) { return a + b; }
    }
}

Program.cs

//This is in LoadWithReflection.exe
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Reflection;

namespace LoadWithReflection
{
    class Program
    {
        static void Main(string[] args)
        {
            Assembly Lib = Assembly.LoadFrom("LibFunctions.dll");
            Type instanceThingType;
            Type staticThingType;
            Object instanceThingObject;

            if (null != (instanceThingType = Lib.GetType("LibFunctions.InstanceThing")))
            {
                instanceThingObject = Activator.CreateInstance(instanceThingType);
                MethodInfo mi = instanceThingType.GetMethod("Sum");
                object resultI = mi.Invoke(instanceThingObject, new object[] { 1, 2 });
                Console.WriteLine(resultI.ToString());
            }
            else { Console.WriteLine("Type not found"); }

            if (null != (staticThingType = Lib.GetType("LibFunctions.StaticThing")))
            {
                MethodInfo ms = staticThingType.GetMethod("Sum");
                object resultS = ms.Invoke(null, new object[] { 3, 4 });
                Console.WriteLine(resultS.ToString());
            }
            else { Console.WriteLine("Type not found"); }

            Console.WriteLine("Finished");
            Console.Read();
        }
    }
}

StaticThing.cs

//This is in LibFunctions.dll
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace LibFunctions
{
    public static class StaticThing
    {
        public static int Sum(int a, int b) { return a + b; }
    }
}