Delphi-PRAXiS - Delphi zeichnet nicht in delphix

hi,
für mich ist derectx noch absolutes neuland

ich habe dies mal von neobrothers abgeschrieben aber leider sehe ich kein viereck, wieso ?
Delphi-Quellcode:
			type

  PD3DVertex = ^TD3DVertex;

  TD3DVertex = record

    p      : TD3DXVector3;

    n      : TD3DXVector3;

    tu, tv : Single;

  end;

var

  Form1: TForm1;

  DXReady: boolean = false;

  //DirectX Devices...

  D3D8    : IDirect3D8;

  D3DDev8 : IDirect3DDevice8;

  d3ddm   : TD3DDISPLAYMODE;

  d3dpp   : TD3DPRESENT_PARAMETERS;

  viereckvb : IDirect3DVertexBuffer8;

  viereck: array [0..3] of TD3DVertex;

implementation

{$R *.DFM}

const

  D3DFVF_D3DVERTEX = D3DFVF_XYZ or D3DFVF_NORMAL or D3DFVF_TEX1;

procedure TForm1.AppOnIdle(Sender: TObject; var Done: Boolean);

begin

 D3DDEV8.Clear(0, nil, D3DCLEAR_ZBUFFER or D3DCLEAR_TARGET, D3DCOLOR_XRGB(0, 0, 255), 1, 0);

 D3DDev8.BeginScene;

   D3DDEV8.SetVertexShader(D3DFVF_D3DVERTEX);

   D3DDEV8.SetStreamSource(0, viereckvb, sizeof(TD3DVertex));

   D3DDEV8.DrawPrimitive(D3DPT_TRIANGLESTRIP, 0, 1);

 D3DDev8.EndScene;

 D3DDev8.Present(nil, nil, 0, nil);

end;

procedure TForm1.FormCreate(Sender: TObject);

var

  ptr : PByte;

begin

  D3D8 := Direct3DCreate8(D3D_SDK_VERSION);

  if D3D8 = NIL then exit;

  if failed(D3D8.GetAdapterDisplayMode(D3DADAPTER_DEFAULT, d3ddm)) then exit;

  Fillchar(d3dpp, sizeof(d3dpp), 0);

  d3dpp.Windowed := TRUE;

  d3dpp.SwapEffect := D3DSWAPEFFECT_DISCARD;

  d3dpp.BackBufferFormat := d3ddm.Format;

  d3dpp.EnableAutoDepthStencil := true;

  d3dpp.AutoDepthStencilFormat := D3DFMT_D16;

  if failed(D3D8.CreateDevice(D3DADAPTER_DEFAULT, D3DDEVTYPE_HAL, form1.handle,

                              D3DCREATE_SOFTWARE_VERTEXPROCESSING, d3dpp, D3DDEV8)) then exit;

  Application.OnIdle := AppOnIdle;

  viereck[0].p := d3dxvector3(-100, 0, -100);

  viereck[0].n := d3dxvector3(0, 1, 0);

  viereck[0].tu := 0;

  viereck[0].tv := 0;

  viereck[1].p := d3dxvector3(-100, 0, 100);

  viereck[1].n := d3dxvector3(0, 1, 0);

  viereck[1].tu := 0;

  viereck[1].tv := 1;

  viereck[2].p := d3dxvector3(100, 0, -100);

  viereck[2].n := d3dxvector3(0, 1, 0);

  viereck[2].tu := 1;

  viereck[2].tv := 0;

  viereck[3].p := d3dxvector3(100, 0, 100);

  viereck[3].n := d3dxvector3(0, 1, 0);

  viereck[3].tu := 1;

  viereck[3].tv := 1;

  D3DDEV8.CreateVertexBuffer(SizeOf(viereck), D3DUSAGE_WRITEONLY,

                                             D3DFVF_D3DVERTEX, D3DPOOL_DEFAULT,

                                             viereckvb);

  viereckvb.Lock(0, SizeOf(viereck), ptr, 0);

  Move(viereck, ptr^, SizeOf(viereck));

  viereckvb.Unlock;

end;