Strategy Error

[IISSG]

Hi,
I keep getting this error could you please advise on the problem.
"Error on calling 'OnBarUpdate' methog for strategy--You are accessing an index with a value that is invalid sinse its out of range.IE accessing a series [barsAgo] witha value of 5 when there are only 4 bars on the chart."
if (Bars.FirstBarOfSession)
if (BarsInProgress == 0)
{
priorTradesCount = Performance.AllTrades.Count;
priorTradesCumProfit = Performance.AllTrades.TradesPerformance.Currency.C umProfit;
}
if (Performance.AllTrades.TradesPerformance.Currency. CumProfit - priorTradesCumProfit >= 100
|| Performance.AllTrades.TradesPerformance.Currency.C umProfit - priorTradesCumProfit <= -400
|| Performance.AllTrades.Count - priorTradesCount > 2)
return;
{
//return;
}
if (Open[0] < Close[1] - Close[1]/1000* gapsize)

{
EnterShortLimit(Contracts, Close[0], "Short");

}
if (BarsInProgress == 0)
if (Open[0] > Close[1] + Close[1]/1000 * gapsize)
{
EnterLongLimit(Contracts, Close[0],"Long");
}

[NinjaTrader_Bertrand]

Please try adding this check here to the OnBarUpdate() start.