@reference0 must be defined error message when creating parameters in for loop before SQL insert query

I need to parameterise the query in the for loop, but VS2013 keeps telling me that @reference0 must be defined.



Any reason why this keeps happening?

            var dbConnect = new DbConnect();
            var cmd = new MySqlCommand();
            dbConnect.OpenConnection();

            var query =
                "INSERT INTO booking (operator_id, plot_id, postcode, datetime, stops, " +
                "mileage, price, passengers, name, note, phone, status, reference) " +
                "VALUES (@operator_id, @plot_id, @postcode, @datetime, @stops, " +
                "@mileage, @price, @passengers, @name, @note, @phone, @status, @reference);";

            for (var i = 0; i < _waypointList.Count; i++)
            {
                query +=
                        @"INSERT INTO waypoint 
                        (booking_id, sequence, address, lat, lng, reference) 
                        VALUES 
                        ((select id FROM booking WHERE reference=@reference" + i + @"),
                        @sequence" + i + @", 
                        @address" + i + @", 
                        @lat" + i + @", 
                        @lng" + i + @", 
                        @reference" + i + ")";
                cmd.Parameters.AddWithValue(("@reference" + i), _reference);
                cmd.Parameters.AddWithValue(("@sequence" + i), i);
                cmd.Parameters.AddWithValue(("@address" + i), _waypointList[i]);
                cmd.Parameters.AddWithValue(("@lat" + i), _lat);
                cmd.Parameters.AddWithValue(("@lng" + i), _lng); 
            }

            Console.WriteLine(query);
            cmd = new MySqlCommand(query, DbConnect.Connection);
            cmd.Parameters.AddWithValue(("@operator_id"), _operatorId);
            cmd.Parameters.AddWithValue(("@plot_id"), _plotId);
            cmd.Parameters.AddWithValue(("@postcode"), _postcode);
            cmd.Parameters.AddWithValue(("@datetime"), _datetime);
            cmd.Parameters.AddWithValue(("@stops"), _stops);
            cmd.Parameters.AddWithValue(("@mileage"), _mileage);
            cmd.Parameters.AddWithValue(("@price"), _price);
            cmd.Parameters.AddWithValue(("@passengers"), _passengers);
            cmd.Parameters.AddWithValue(("@name"), _name);
            cmd.Parameters.AddWithValue(("@note"), _note);
            cmd.Parameters.AddWithValue(("@phone"), _phone);
            cmd.Parameters.AddWithValue(("@status"), Status);
            cmd.Parameters.AddWithValue(("@reference"), _reference);

            cmd.ExecuteNonQuery();
            dbConnect.CloseConnection();