public string SaveInvoiceDetails(string fname, string mname, string lname, string phone, string email, string amount)
    {
        string         ret = "";
        PhoneValidator ph  = new PhoneValidator();

        if (!bll.IsValidEmailAddressOptional(email))
        {
            ret = "Please Provide a valid email address";
        }
        else if (!ph.PhoneNumbersOk(phone) && !phone.Equals(""))
        {
            ret = phone + " is not a valid phone number";
        }
        else
        {
        }
        return(ret);
    }