Minimum and Maximum methods

I have an indicator that needs to know the min and max of a particular currency.

I'm using the Minimum and Maximum methods in the Initialize() method of my indicator.

double x = MarketSeries.Open.Maximum(3500);

Now, when I reference the indicator in my cBot I've noticed that the indicator doesn't receive the same value.   The return value for MarketSeries.Open.Maximum(3500) is different when it's executed via a cBot.     Even if I ensure that backtesting has at least 3500 periods it's still different. 

Thanks