Vista - [V2] Add-type can not create Composite Struct ?

add-type @"
using System;
using System.Runtime.InteropServices;
namespace mystruct
{
    [StructLayout(LayoutKind.Sequential)]
    public struct RECT
    {
        public Int32 left;
        public Int32 top;
        public Int32 right;
        public Int32 bottom;
    }
    [StructLayout(LayoutKind.Sequential)]
    public struct WINDOWINFO
    {
        public UInt32 cbSize;
        public RECT rcWindow;
        public RECT rcClient;
        public UInt32 dwStyle;
        public UInt32 dwExStyle;
        public UInt32 dwWindowStatus;
        public UInt32 cxWindowBorders;
        public UInt32 cyWindowBorders;
        public UInt16 atomWindowType;
        public UInt16 wCreatorVersion;
    }
}
"@

$w=new-object mystruct.windowinfo
$w
$w.wCreatorVersion=102
$w.wCreatorVersion 
#102

 
$w.rcClient
$w.rcClient.left=10
$w.rcClient.Left
#0
$r=new-object Mystruct.RECT
$r.left=12
$r.left
#12
$w.rcClient.left=$r.left
$w.rcClient.left
#0
$w.rcClient=$r
$w.rcClient.Left
#12
$w.rcClient.left=10
$w.rcClient.Left
#12