图像显示问题

为什么Image2里不能显示图像！我调试的时候说destbmp为空是怎么回事？procedure TForm1.Button1Click(Sender: TObject);
var  sourcbmp,destbmp:TBitmap ;
     sourRect,destRect:TRect;
begin
     sourcbmp:=TBitmap.Create;
     destbmp:=TBitmap.Create;   //  destbmp.Palette:=sourcbmp.Palette;
     sourcbmp.LoadFromFile('D:\我的文档\美图图库\1.bmp');
     destbmp.PixelFormat:=sourcbmp.PixelFormat;
     Image1.Picture.Bitmap.Assign(sourcbmp);
     destRect:=Rect(0,0,sourcbmp.Width,sourcbmp.Height);
    // sourRect:=Rect(0,0,sourcbmp.Width,sourcbmp.Height);
     destbmp.Canvas.CopyRect(destRect,sourcbmp.Canvas,destRect);
  //   if BitBlt(Destbmp.Handle,0,0,sourcbmp.Width,sourcbmp.Height,Sourcbmp.Handle,0,0,SRCCOPY) then
   //  ShowMessage('1');
      Image2.Picture.Bitmap.Assign(Destbmp);
end;