out of range index error with Draw.Text

[dadarara]

What is the best way to eliminate this error:

Error on calling 'OnBarUpdate' method on bar 21: You are accessing an index with a value that is invalid since it is out-of-range

Bars required to trade is 20

I have this code:

if (ShowLines ) Draw.Text(this, "Lable1", false,MyValue.ToString(), Convert.ToInt32((ChartBars.ToIndex-ChartBars.FromIndex)*0.1), LowOfRange-TickSize*2, 0, Brushes.Green, smallFont, TextAlignment.Justify, Brushes.Transparent, Brushes.Transparent, 0);

thought about :
if (ShowLines && CurrentBar > 50) Draw.Text(this .....

not working...

[NinjaTrader_AlanP]

Hello dadarara,

Thank you for your note.

If you replace the following with 5, does the code work without exception?

Convert.ToInt32((ChartBars.ToIndex-ChartBars.FromIndex)*0.1)

I look forward to your reply.

[dadarara]

yes it does.
but I was wondering why the number of visible bars on screen at the moment of strategy initiation would matter to historical calculation?
and what would be the better practice if I wish to draw.text at some offset from the right of the chart that should also be related to the total number of bars.
cant be 5. on chart of 60min it might work. but with 30sec chart there are much more bars so 5 would be insignificant number.

[dadarara]

I am not yet clear of how to do it, please help

[NinjaTrader_AlanP]

Hello dadarara,

You should ensure that CurrentBar > Convert.ToInt32((ChartBars.ToIndex-ChartBars.FromIndex)*0.1) if you wish to use that value as an offset. See current bar checks,

https://ninjatrader.com/support/forum/forum/ninjascript-educational-resources/tips/3287-make-sure-you-have-enough-bars-in-the-data-series-you-are-accessing?t=3170

Why would passing a 5 for the BarsAgo not work for drawing text 5 bars back from the CurrentBar?

I look forward to your reply.