Hi Steve,
Most likely you did not assign chart(s) to the legend using the DisplayOnLegend property:
NLegend legend = new NLegend();
nChartControl1.Panels.Add(legend);
NCartesianChart chart = new NCartesianChart();
nChartControl1.Panels.Add(chart);
chart.Series.Add(new NBarSeries());
chart.DisplayOnLegend = legend;
Note that the chart and legend must be added to the document.
Best Regards,
Nevron Support Team