Недопустимый двоичный формат входного потока - C#

namespace pr
{
    [Serializable]
    class logic
    {
        StringBuilder organisation;
        StringBuilder telephone;
        StringBuilder contact;
        StringBuilder adress;
 
        public logic()
        {
            organisation = new StringBuilder("ГАЗПРОМ", 80);
            adress = new StringBuilder("улица Руставелли",100);
            telephone = new StringBuilder("88006005050", 11);
            contact = new StringBuilder("www.bbb.com", 100);
        }
 
        public logic(string organisation, string adress, string telephone, string contact)
        {
            this.organisation = new StringBuilder(organisation, 80);
            this.adress = new StringBuilder(adress, 100);
            this.telephone = new StringBuilder(telephone, 11);
            this.contact = new StringBuilder(contact, 100);
        }
 
        public void AddToFile(string path)
        {
            FileStream f = new FileStream(path, FileMode.Append);
            BinaryFormatter bw = new BinaryFormatter();
            bw.Serialize(f, this, null);
            f.Close();
        }
 
        public static string Show(string path)
        {
            BinaryFormatter formatter = new BinaryFormatter();
            string ans = "";
 
            using (FileStream fs = new FileStream(path, FileMode.OpenOrCreate))
            {
                while (fs.Position < fs.Length)
                {
                    logic newLogic = (logic)formatter.Deserialize(fs);
                    ans += newLogic.organisation + "," +newLogic.adress+","+ newLogic.telephone + "," + newLogic.contact + "," + "";
                }
            }
            return ans;
        }
        public long find(string path)
        {
            BinaryFormatter formatter = new BinaryFormatter();
            using (FileStream fs = new FileStream(path, FileMode.OpenOrCreate))
            {
                while (fs.Position < fs.Length)
                {
                    long pos = fs.Position;
                    logic newLogic = (logic)formatter.Deserialize(fs);
                    if (newLogic.organisation.Equals(this.organisation))
                        return pos;
                }
            }
            return -1;
        }
        public void correct(string path, long pos)
        {
            BinaryFormatter formatter = new BinaryFormatter();
            using (FileStream fs = new FileStream(path, FileMode.OpenOrCreate))
            {
                fs.Seek(pos, SeekOrigin.Begin);
                formatter.Serialize(fs, this, null);
            }
        }
    }
}