Error on calling 'OnStateChange' when adding a data series

[AimHigh]

Hello,

I'm trying to add a secondary data series using this code:

protected override void OnStateChange()
{
if (State == State.SetDefaults)
{
//Some Code
}
else if (State == State.Configure)
{
AddDataSeries(Instrument.FullName, new BarsPeriod { BarsPeriodType.Minute, Value = 5 }, "US Equities RTH");
}
else if (State == State.DataLoaded)
{
// Some Code
}
}​​

My problem is that I get the following error when trying to optimize my strategy:
Error on calling 'OnStateChange' method: Object reference not set to an instance of an object.
I know for sure the problematic line is the AddDataSeries as I do not get that error when I comment it out.
Any ideas what am I doing wrong?
TIA!