将字符串转为Image时的有关问题,求解决

将字符串转为Image时的问题,求解决

C# code

public void ShowPictureOfString(string text)        {            byte[] buf = Convert.FromBase64String(text);             MemoryStream ms = new MemoryStream(buf);            /*报错: 无效的参数*/            Image img =Image.FromStream(ms);  //From Stream to a new Image             this.pictureBox1.Image = img;            ms.Close(); ms.Dispose();}