Difference in Tick Volume between cAlgo and cTrader

Hello,

I used the code attached below just to count the tick volume and I noticed that cAlgo only counts the changes in the price on the Bid Price. It should count Bid and Ask price changes. I like to know if this issue regards the platform or the broker (Im currently using the broker FxPro).

Thank you.

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

namespace cAlgo
{
    [Robot(TimeZone = TimeZones.UTC, AccessRights = AccessRights.None)]
    public class TickCount : Robot
    {
        protected int c = 0;

        protected override void OnBar()
        {
            Print("OpenTime= " + MarketSeries.OpenTime[MarketSeries.OpenTime.Count - 2] + " TickVolume= " + c);
            c = 0;
        }

        protected override void OnTick()
        {
            c++;
        }
    }
}