What is NaN in my DataSeries

[astrolobe]

I am printing out the values of my custom DataSeries, and all the values are NaN. What is NaN, and any clues what could be causing it?

This is my code:

double slope = Math.Atan(Slope(ADX(14), 20,0)) * 180/Math.PI;
SlopeSeries.Set(slope);
myDataSeries.Set(SMA(SlopeSeries, 3)[0]);
Print ("myDataSeries = " + myDataSeries[0]);

thanks

[NinjaTrader_JoshP]

Generally means an invalid number. Please try using Print()s along each step and see where the logic breaks down.