File.WriteAllText and new line

Hello

I wrote this code, but new string does not go to a new line in file.

                address = "http://" + cellAdress.ToString()+"\n";
                String FilePath_address = Application.StartupPath + @"\address.txt";
                if (System.IO.File.Exists(FilePath_address))
                {                    System.IO.File.WriteAllText(FilePath_address, address);
                }
            }