Refer to instrument in indicator

[eleven]

I need some assistance. Let's say that I want to create a custom indicator that calculates "aapl close[0] / msft close[0]" and plots it. I understand how to plot, but what I don't understand is how to refer to specific a instrument in the code.

My intention is to create a custom breadth indicator, but I don't know how to refer to $ADVN and $DECN in the code.

I appreciate any help or guidance on this. Thanks.


*** Edit

        protected override void Initialize()
        {
            Add(new Plot(Color.FromKnownColor(KnownColor.Orange), PlotStyle.Line, "Breadth"));
            Add(new Plot(Color.FromKnownColor(KnownColor.Green), PlotStyle.Line, "MA"));
            Add(new Plot(Color.FromKnownColor(KnownColor.DarkViolet), PlotStyle.Line, "Diff"));
            Add(new Line(Color.FromKnownColor(KnownColor.DarkOliveGreen), 0, "Zero"));
            CalculateOnBarClose    = true;
            Overlay                = false;
            PriceTypeSupported    = false;
            Add("AAPL", PeriodType.Minute, 5);
        }

What am I doing wrong here? I get "No overload for method 'Add' takes '3' arguments" error for the last Add (with AAPL). Are there not 3 arguments already?

[NinjaTrader_Bertrand]

eleven, working with multiple timeframes or instruments is only supported in NinjaScript strategies with NinjaTrader 6.5 - http://www.ninjatrader-support.com/H...struments.html

[eleven]

Thanks Bertrand.