How to change chart background color from strategy?

[fx.practic]

Hello.

To change chart background color (and bar colors) from indicator I this simple way, that works perfectly:

if( ChartControl != null && Bars != null )
{
    ChartControl.Properties.ChartBackground =  System.Windows.Media.Brushes.Black;
    ChartBars.Properties.ChartStyle.UpBrush   = WmBrushes.Violet;
} 

But, in strategies, this way work from time to time (I tied to use it in all States, and in OnBarUpdate() method.
In one of my strategies it don't work at all.

Is there another [more correct] way to do it from strategy [and, may be, from indicator]?

[fx.practic]

SOLVED:

Manual, Best Practices
"For objects which exist on the UI (e.g., ChartControl, ChartPanel, ChartBars, NTWindow, etc.) wait until the State has reached State.Historical. This practice is correct for both reading properties or should you wish to add custom elements to the existing UI."

In hosted indicator specified code must be placed in State.Historical

[fx.practic]

Still have problem to change background color when strategy run in StrategyAnalyser.
Can't change color, even, from OnBarUpdate()

Need good advice, please!

[NinjaTrader_ChelseaB]

Hello fx.practic,

When using the Strategy Analyzer the ChartControl object is null.

From the help guide:

"Note: The ChartControl object is ONLY guaranteed to be available when a NinjaScript type initiates from a Chart Window. There are situations where an indicator or strategy starts from another Windows (such as the Control Center's Strategies Grid, or from a Strategy Analyzer), where the ChartContol object is NOT accessible. Therefore, the ChartControl object should always be safely accessed (e.g., from within a try-catch, or conditionally using null reference checks)"

https://ninjatrader.com/support/helpGuides/nt8/en-us/chartcontrol.htm

[fx.practic]

Thank You.
I start to remember this part of manual while reading Your answer.
Thank You, sorry for the question.

NT8 manual is like Saint Book - I should read it again and again...