how to add Trailing stop loss? Sample RSI cBot

using System;
using System.Linq;
using cAlgo.API;
using cAlgo.API.Indicators;
using cAlgo.API.Internals;
using cAlgo.Indicators;

namespace cAlgo.Robots
{
    [Robot(TimeZone = TimeZones.UTC, AccessRights = AccessRights.None)]
    public class wisdom101 : Robot
    {
        [Parameter("Source")]
        public DataSeries Source { get; set; }

        [Parameter("Periods", DefaultValue = 14)]
        public int Periods { get; set; }

        [Parameter("Stop Loss (pips)", DefaultValue = 10, MinValue = 10)]
        public int StopLoss { get; set; }

        [Parameter("Volume", DefaultValue = 80, MinValue = 80)]
        public int Volume { get; set; }

        private RelativeStrengthIndex rsi;

        protected override void OnStart()
        {
            rsi = Indicators.RelativeStrengthIndex(Source, Periods);
        }

        protected override void OnTick()
        {
            if (rsi.Result.LastValue <= 30)
            {

                Close(TradeType.Sell);
                Open(TradeType.Buy);

            }
            else if (rsi.Result.LastValue >= 70)
            {
                Close(TradeType.Buy);
                Open(TradeType.Sell);
            }
        }

        private void Close(TradeType tradeType)
        {
            foreach (var position in Positions.FindAll("BTCWISDOMV2", Symbol, tradeType))
                ClosePosition(position);
        }

        private void Open(TradeType tradeType)
        {
            var position = Positions.Find("BTCWISDOMV2", Symbol, tradeType);

            if (position == null)
                ExecuteMarketOrder(tradeType, Symbol, Volume, "BTCWISDOMV2", StopLoss, null);

        }

        protected override void OnTick()
        {
            if (position == null)
                return;

            // Trailing
            if (position.TradeType == TradeType.Sell)
            {
                double distance = position.EntryPrice - Symbol.Ask;

                if (distance >= Trigger * Symbol.PipSize)
                {
                    double newStopLossPrice = Symbol.Ask + TrailingStop * Symbol.PipSize;
                    if (position.StopLoss == null || newStopLossPrice < position.StopLoss)
                    {
                        Trade.ModifyPosition(position, newStopLossPrice, position.TakeProfit);
                    }
                }

            }
            else
            {
                double distance = Symbol.Bid - position.EntryPrice;

                if (distance >= Trigger * Symbol.PipSize)
                {
                    double newStopLossPrice = Symbol.Bid - TrailingStop * Symbol.PipSize;
                    if (position.StopLoss == null || newStopLossPrice > position.StopLoss)
                    {
                        Trade.ModifyPosition(position, newStopLossPrice, position.TakeProfit);





                    }
                }
            }
        }
    }
}

It is giving the error below:

Error CS0111: Type 'cAlgo.Robots.wisdom101' already defines a member called 'OnTick' with the same parameter types