I tried doing that but still the legend didn't gt displayed.

Is this for a composite chart or non-composite? are you creating series or using databinding? can you post a code snippet which shows how you set up your chart? Thanks.

It's a series.

formatString(cs.CashFlowMap["Month"].ToString(), "Month"), false)));

this.ultraChart1.Series.Add((scl1));

When adding series to the chart, the legend only displays the series that have a label.

Try doing this:
scl.Label = "ScheduledPrincipal";
scl1.Label = "Interest";

Thanks Max, It worked.