update the sql table doesnt work??!!!

Question

my sql table is not updated, when i do???!!, the codes are as folow:

string connectionStringid = ConfigurationManager.ConnectionStrings["CustomerDB"].ConnectionString;
connad = new SqlConnection(connectionStringad);
commandad = new SqlCommand("", connad); 

which are class variables. the folowing codes for insert and update, insert works, but not update???!!:

public static string AddAd(Customerad customerad, int Id)
{
    string result;
    string q = string.Format("select * from customerad1 where Email='{0}' and Title='{1}'", customerad.Email, customerad.Title);
    try
    {
        connad.Open();
        commandad.CommandText = q;
        int amountOfUsers = Convert.ToInt32(commandad.ExecuteScalar());
        if (amountOfUsers < 1) //new user
        {
            commandad.CommandText = @"INSERT INTO customerad1 (Name, Email, Phone, Country, ZipCode, Category, Title, Price, Images, Date_Time, Description, Bussiness, Payment) VALUES
            ('" + customerad.Name + "','" + customerad.Email + "','" + customerad.Phone + "','" + customerad.Country + "','" + customerad.ZipCode + "','" + customerad.Category + "','" + customerad.Title + "','" + customerad.Price + "','" + customerad.Images + "','" + customerad.Date_Time + "','" + customerad.Description + "','" + customerad.Bussiness + "','" + customerad.Payment + "')";
            commandad.ExecuteNonQuery();
            result = "Ad registered!";
        }
        else //user exist
        {
            commandad.CommandText = @"UPDATE customerad1 SET ([Name]='" + customerad.Name + "', [Email]='" + customerad.Email + "', " +
                    "[Phone]='" + customerad.Phone + "', " +
                    "[Country]='" + customerad.Country + "', [ZipCode]='" + customerad.ZipCode + "', [Category]='" + customerad.Category + "', " +
                    "[Title]='" + customerad.Title + "', [Price]='" + customerad.Price + "', [Images]='" + customerad.Images + "', " +
                    "[Date_Time]='" + customerad.Date_Time + "', [Description]='" + customerad.Description + "', [Bussiness]='" + customerad.Bussiness + "', [Payment]='" + customerad.Payment + "') where [Id]='" + Id + "' ";
            commandad.ExecuteNonQuery();
            result = "Ad updated!";
        }
    }
}

i cannot find the problem... please help me, i appreciate... kind regards