Multi-Instrument Strategy OnBarUpdate Sequence

[fwalton]

I have a Strategy and a StrategyPlot as follows:
Primary Instrument: 'MSFT'
Secondary Instrument: '^SP500'
Period: Daily
BarsBack: 4

Initialize()
{
CalculateOnBarClose = true;
BarsRequired = 0;
Add("^SP500", PeriodType.Day, 1);

Add(StrategyPlot(0));
StrategyPlot(0).PanelUI = 1;
}


To investigate data availability for all instruments for a particular bar I placed this debug code in OnBarUpdate:
OnBarUpdate()
{
string logText = "";
logText += String.Format("BarsInProgress:{0} Instrument:{1} CurrentBar:{2} Date:{3}", BarsInProgress, Instruments[BarsInProgress], CurrentBar, Time[0]);
Log(logText, LogLevel.Information);
}

It produced the following output (from newest to oldest)
BarsInProgress: 1 Instrument:^SP500 CurrentBar:2 Date:6/29/2009
BarsInProgress: 0 Instrument:MSFT CurrentBar:2 Date:6/29/2009
BarsInProgress: 1 Instrument:^SP500 CurrentBar:1 Date:6/26/2009
BarsInProgress: 0 Instrument:MSFT CurrentBar:1 Date:6/26/2009
BarsInProgress: 1 Instrument:^SP500 CurrentBar:0 Date:6/25/2009
BarsInProgress: 0 Instrument:MSFT CurrentBar:0 Date:6/25/2009

Since I want to do a calculation involving values from both DataSeries it seemed I should add the following condition to ensure both DataSeries values for the CurrentBar were available:
OnBarUpdate()
if (BarsInProgress == 1)
{
//do some calculation and assign it to the plot
StrategyPlot(0).Value.Set(Closes[0][0] + Closes[1][0]);
}

However, no plot lines were drawn. If I changed the condition to:
if (BarsInProgress == 0)
the plot worked fine.

1) What's the timing relationship between 'OnBarUpdate' and 'Plot.Value.Set'?

2) What is the best 'BarsInProgress' practice for performance and stability when using multiple instruments in the same timeframe?

Thanks
- Fred

[NinjaTrader_Austin]

StrategyPlot was developed as a temporary solution, so to make a long story short, we recommend you only use it with Primary Bars when BarsInProgress == 0.

NinjaTrader 7 will include the capability to develop multi-instrument indicators and that will make what you're trying to do much easier.

[fwalton]

Ok, the short story is clear.
I'll stay within recommendations for 6.5, and hold my other questions until I've re-created this and other functionality in 7.0

Keep up the great work.

- Fred