Pantonescolor tiff file throwing an error in Bitmap conversion.

static Bitmap RedrawImage(string FileName, int TargetSize)
        {
            try
            {
                Bitmap newImage;
                using (Bitmap oldImage = new Bitmap(FileName))
                {
                    Size newSize = CalcuateDimentions(oldImage.Size, TargetSize);
                    newImage = new Bitmap(newSize.Width, newSize.Height, PixelFormat.Format24bppRgb);

                    Graphics canvas = Graphics.FromImage(newImage);
                    canvas.SmoothingMode = SmoothingMode.HighQuality;
                    canvas.InterpolationMode = InterpolationMode.HighQualityBicubic;
                    canvas.PixelOffsetMode = PixelOffsetMode.HighQuality;

                    canvas.DrawImage(oldImage, new System.Drawing.Rectangle(new Point(0, 0), newSize));
                    oldImage.Dispose();
                }
                return newImage;
            }
            catch (Exception ex)
            {
                throw new Exception("Error attempting to redraw the image", ex);
            }
        }