Errors getting indicator values

[Displacer]

I'm trying to create an Indicator that is using current and historical values of an ATR.

I can call:

[INDENT]if(BarsInProgress > 20)[/INDENT][INDENT=2]return;[/INDENT][INDENT]{[/INDENT][INDENT=2]atrValue = ATR(10)[0];[/INDENT][INDENT]}[/INDENT]

And have no issues but if I call:

[INDENT]
if(BarsInProgress > 20)[/INDENT][INDENT=2]return;[/INDENT][INDENT]{[/INDENT][INDENT=2]prevATR = ATR(10)[1];[/INDENT][INDENT]}[/INDENT]

I get the following error:
Error on calling 'OnBarUpdate' method on bar 0: You are accessing an index with a value that is invalid since it is out-of-range.
I.E. accessing a series [barsAgo] with a value of 5 when there are only 4 bars on the chart.

I've tried many different methods to try to get the ATR's historical values including attempting to store the values in a Series<T>. In this attempt for example

else if (State == State.DataLoaded)[INDENT]{[/INDENT][INDENT=2]ATRdata = new Series<double>(this, MaximumBarsLookBack.Infinite);[/INDENT][INDENT]}[/INDENT]
  
protected override void OnBarUpdate()[INDENT]{[/INDENT][INDENT=2]if (BarsInProgress > 20)[/INDENT][INDENT=3]return;[/INDENT][INDENT=2]{[/INDENT][INDENT=3]ATRdata[0] = ATR(10)[0];[/INDENT][INDENT=3]Print("Current ATR is " ATRdata[0]);[/INDENT][INDENT=3]prevATR = ATRdata[1];[/INDENT][INDENT=3]Print("Previous ATR is " + prevATR);[/INDENT][INDENT=2]}[/INDENT][INDENT]}[/INDENT]

But still get " Error on calling 'OnBarUpdate' method on bar 0:" when trying to get the prevATR value.

I'm rather new to NT8 coding.
Any help would be appreciated. Perhaps something I missed.

[NinjaTrader_Jesse]

Hello Displacer,

It looks like you have a few problems here. I'm am basing my reply off the fact that you used the curly braces with the BarsInProgress condition, I take it that you meant 20 bars here.

To use 1 BarsAgo with the ATR you would need the following:

if(CurrentBar < 1) return;
atrValue = ATR(10)[1];

The 1 bar would be required for 1 bars ago, you can still use 20 as well if you wanted but the minimum would be 1 for that statement.

The curly braces you used makes the BarsInProgress condition confusing, if you actually did mean for that BarsInProgress condition then it would instead look like:

if (BarsInProgress > 20) return;
if(CurrentBar < 1) return;
atrValue = ATR(10)[1];

[Displacer]

Thank you! This solved my issue.