Reflection Emit: how to build constructor for this

The code I want to build dynamically is as follows:

public class Sample
{
    public Sample()
    {
        Items = new ObservableTestCollection<Sample>(this);
    }
    public Sample(IEnumerable<Sample> source)
    {
        Items = new ObservableTestCollection<Sample>(this, source);
    }
    public ObservableTestCollection<Sample> Items;

}

The Source of ObservableTestCollection is as follows:

public class ObservableTestCollection<T> : ObservableCollection<T>
{
    public T Parent;       
    public ObservableTestCollection(T parent)
    {
        Parent = parent;
    }
    public ObservableTestCollection(T parent, IEnumerable<T> source) : base(source)
    {
        Parent = parent;
    }
}

Code I write as

const string assemblyName = "SampleAssembly";
const string fieldName = "Items";
const string typeName = "Sample";
const string assemblyFileName = assemblyName + ".dll";

AppDomain domain = AppDomain.CurrentDomain;
AssemblyBuilder assemblyBuilder = domain.DefineDynamicAssembly(new AssemblyName(assemblyName), AssemblyBuilderAccess.RunAndSave);
ModuleBuilder moduleBuilder = assemblyBuilder.DefineDynamicModule(assemblyName, assemblyFileName);

TypeBuilder typeBuilder = moduleBuilder.DefineType(typeName, TypeAttributes.Class | TypeAttributes.Public);

Type[] ctorParameters = new Type[] { typeBuilder };
Type typeOfCTS = typeof(ObservableTestCollection<>);
Type genericTypeOTS = typeOfCTS.MakeGenericType(typeBuilder);


FieldBuilder fieldBuilder = typeBuilder.DefineField(fieldName, genericTypeOTS, FieldAttributes.Public);

        //first constructor
ConstructorBuilder ctorBuilder = typeBuilder.DefineConstructor(MethodAttributes.Public, CallingConventions.HasThis, Type.EmptyTypes);
ILGenerator generator = ctorBuilder.GetILGenerator();
        generator.Emit(OpCodes.Ldarg_0); //load this
        generator.Emit(OpCodes.Call, typeof(object).GetConstructor(Type.EmptyTypes)); //call object constructor

var ci = typeOfCTS.GetConstructors()[0];
generator.Emit(OpCodes.Newobj, ci);            
generator.Emit(OpCodes.Stfld, fieldBuilder); // store into Items
generator.Emit(OpCodes.Ret); //return


//second constructor
var typeOfIE = typeof(IEnumerable<>);
var genericTypeIE = typeOfIE.MakeGenericType(typeBuilder);          
ctorParameters = new Type[] {genericTypeIE };
ctorBuilder = typeBuilder.DefineConstructor(MethodAttributes.Public, CallingConventions.HasThis, ctorParameters);

ctorParameters = new Type[] { typeBuilder, genericTypeIE };
generator = ctorBuilder.GetILGenerator();
generator.Emit(OpCodes.Ldarg_0); //load this

ci = typeOfCTS.GetConstructors()[1];
generator.Emit(OpCodes.Newobj, ci);
generator.Emit(OpCodes.Stfld, fieldBuilder); // store into Items
generator.Emit(OpCodes.Ret); //return
Type type = typeBuilder.CreateType();
var obj = Activator.CreateInstance(type);
assemblyBuilder.Save(assemblyFileName);

I can't create instance of Sample Any one can help me correct this problem.

Your help would be much appreciated.