Your syntax is incorrect.

For the correct syntax see:
NinjaTrader 8

Thanks for your response. I don't think the syntax is incorrect as I have already made the code-breaking adjustments required from NT7 to NT8 and it compiles fine.

The problem is that the primary bars have not been loaded yet by State.Configure (where you are supposed to add additional data series) so you can't really reference them by means of BarsPeriods[0].BarsPeriodType and BarsPeriods[0].Value. In NT7 I used to be able to do this within Initialize().

For an indicator which I'd like to have work on both a daily and minute bar strategy, it's quite annoying having to hard code two separate versions (even more needed if you use different minute bars and you'd like both minute data series the same).

No hardcoding needed; think you didn't get different syntax options right ...

Esp for spreads try (within State.Configure)

AddDataSeries(secondInstrument, BarsPeriod.BarsPeriodType, barValue, Data.MarketDataType.Last);

where barValue is
barValue = Math.Max(1, base.BarsPeriod.Value);

Indicator 'MyIndicator': Error on calling 'OnStateChange' method: Object reference not set to an instance of an object.

Thanks again for your help.

I just tried your syntax, and am getting the same error I was getting using my syntax:



When I do not reference anything to do with BarsPeriod or BarsPeriods though (and hardcode), it works fine. Have you tried it on the latest version of the beta?

I use exactly the above snippet for spreads in the latest NT8 version.
Please post your State.Configure.

The commented lines are what I use normally (the first one doesn't work for me though which is why I'm having this problem). RefInstrument is defined earlier in State.SetDefaults too.

One last thing if you don't mind, perhaps you could try my syntax out as well? I'm starting to think this is a problem specific to my system, so perhaps I'll try installing on another machine over the weekend before I waste any more of your time.

Thanks again!

The [0] line is evidently faulty. Line 1 and 3 are "supposed to work" ... strange.
Just to make sure that the error isn't caused by your RefInstrument the snippet I use for setting the second instrument of my spreads from Properties:

[Description("Second instrument")]
[NinjaScriptProperty]
[Display(Name="2nd Instrument", Order=1, GroupName="Parameters")]
public string secondInstrument
{
get { return secondInstrument; }
set { secondInstrument= value; }
}