Value cannot be null. Parameter name: type at System.Activator.CreateInstance(Type type, Boolean nonPublic)

You are passing an object[] of constructor parameters to the Activator.CreateInstance method but the MoveFile class doesn't seem to have any constructor that takes any parameters. Try the following or create a constructor that takes all these passed parameters as arguments:

Activator.CreateInstance(Assembly.Load("MoveFile").GetType("MoveFile.MoveFile"));