picturebox在将用户定义保存到字节数组时返回错误

我非常需要帮助，因为我根本无法解决这个问题。当它使用资源映像保存到字节数组中时，它工作得很好，但当有用户定义的映像时，它应该使用该映像并将其保存到数组和程序chrash中，我就是找不到问题。

代码：

        //Check for image and if true save it to byte array
        if (pictureBox1.Image != null)
        {               
            using (MemoryStream ms = new MemoryStream())
            {
                pictureBox1.Image.Save(ms, System.Drawing.Imaging.ImageFormat.Bmp);
                arr = ms.ToArray();
            }
        }
        else
        {
            using (MemoryStream ms = new MemoryStream())
            {
                AnimalMotel.Properties.Resources.nophotos.Save(ms, System.Drawing.Imaging.ImageFormat.Bmp);
                arr = ms.ToArray();
            }
        }

ELSE部分在这里工作得很完美，当有一个用户定义的图像时，问题就出现了，然后它崩溃了，给出了这个：

  An unhandled exception of type 
  'System.Runtime.InteropServices.ExternalException' 
  occurred in System.Drawing.dll
  Additional information: A generic error occurred in GDI+.

上一个代码：

        OpenFileDialog openFileDialog1 = new OpenFileDialog();
        openFileDialog1.InitialDirectory = "c:''";
        openFileDialog1.Filter = "(*.Bmp)|*.Bmp|All files (*.*)|*.*";
        openFileDialog1.FilterIndex = 2;
        openFileDialog1.RestoreDirectory = true;
        if (openFileDialog1.ShowDialog() == DialogResult.OK)
        {
            try
            {
                if ((myStream = openFileDialog1.OpenFile()) != null)
                {
                    using (myStream)
                    {
                        pictureBox1.Image = new Bitmap(myStream);
                    }
                }
            }
            catch (Exception ex)
            {
                MessageBox.Show("Error: Could not read file from disk. Original error: " + ex.Message);
            }
        }
    }