How to get OHLC prices of different timeframes in a CBOT

The method to get them in indicators and in a Bot is different it sees cause Cbot doesn't have “index”  and I just tried it like this and it didn't give me the current open price I wanted 

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using cAlgo.API;
using cAlgo.API.Collections;
using cAlgo.API.Indicators;
using cAlgo.API.Internals;

namespace cAlgo.Robots
{
    [Robot(AccessRights = AccessRights.None)]
    public class CountBars : Robot
    {
    
        [Parameter(DefaultValue = "Hello world!")]
        public string Message { get; set; }
        
      
        private Bars Bars15Min; 

        protected override void OnStart()
        {
         
        Bars15Min = MarketData.GetBars(TimeFrame.Minute15);
         
        }

        protected override void OnTick()
        {
         
            double OpenNow = Bars15Min.OpenPrices.Last(0);
            
            Print(OpenNow);
          
       
        }
        
         protected override void OnBar()
        {
            
      
        
        
        }

        protected override void OnStop()
        {
            // Handle cBot stop here
        }
        
        
    
    }
}