Tradestation Return on Account

[pecas]

Hi all,
I have a problem in setting margins in Tradestation 8.7 (with OwnData 2.7).
When I optimize a strategy, Return on Account is computed as TotalProfit/(MaxDrawdown), while it should be TotalProfit/(Margin+MaxDrawDown).
So, where should I specify the Margin in order to have it working for strategy optimization?