Thumbnail not working with DecodeFile... look code

                public static int CalculateInSampleSize(BitmapFactory.Options options, int reqWidth, int reqHeight)
            {
        // Raw height and width of image
        var height = (float) options.OutHeight;
        var width = (float) options.OutWidth;
                var inSampleSize = 1D;
            if (height > reqHeight || width > reqWidth)
            {
                inSampleSize = width > height
                    ? height/reqHeight
                        : width/reqWidth;
            }
            return (int) inSampleSize;
        }

        public static Bitmap DecodeSampledBitmapFromResource(string path, int reqWidth, int reqHeight)
        {
            // First decode with inJustDecodeBounds=true to check dimensions
            var options = new BitmapFactory.Options {InJustDecodeBounds = true};
            BitmapFactory.DecodeFile(path);
            // Calculate inSampleSize
            options.InSampleSize = CalculateInSampleSize(options, reqWidth, reqHeight);
            // Decode bitmap with inSampleSize set
            options.InJustDecodeBounds = false;
            return BitmapFactory.DecodeFile(path);

        }

and then im doing

using (var bmp = DecodeSampledBitmapFromResource(path+"/"+listaFotos[pagina*10], 5, 5))
{
    //Console.WriteLine(caminho+listaFotos[pagina*10]);
    imagem1.SetImageBitmap(bmp);
}

But im getting an image in the normal size that is fucking my memory the same way as without using this... Any ideia?