ChartObjects: draw vertical lines at equidistant intervals

I want to draw vertical lines at equidistant intervals.
The first vertikal line is defined by date and time.
The interval is also a give time, format:  Days Hours Minutes Seconds.

Does someone know how to define the interval?
The code so far:

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

namespace cAlgo
{
    [Indicator(IsOverlay = true, AutoRescale = false, TimeZone = TimeZones.UTC, AccessRights = AccessRights.None)]
    public class MaVe2015 : Indicator
    {
        protected override void Initialize()
        {
            // Initialize and create nested indicators
        }

        public override void Calculate(int index)
        {
            var Day1 = new DateTime(2015, 9, 15, 7, 15, 0);
            ChartObjects.DrawVerticalLine("D1", Day1, Colors.Blue, 1, LineStyle.Solid);
        }
    }
}