I tried to simulate your problem. I added two data series one with 3 points, one with 2 points. The chart rendered correctly. This makes me think you are going to have to massage your data before you bind it.
curveChart.Series.Clear();
curveChart.Series.Add("Series1");
curveChart.Series["Series1"].XValueType = ChartValueType.DateTime;
curveChart.Series["Series1"].Points.AddXY(DateTime.Now, 12.00m);
curveChart.Series["Series1"].Points.AddXY(DateTime.Now.AddDays(1), 13m);
curveChart.Series["Series1"].Points.AddXY(DateTime.Now.AddDays(2), 8m);
curveChart.Series["Series1"].ChartType = System.Windows.Forms.DataVisualization.Charting.SeriesChartType.Line;
curveChart.Series["Series1"].BorderWidth = 3;
curveChart.ChartAreas["0"].AxisX.Interval = 1;
curveChart.Series.Add("Series2");
curveChart.Series["Series2"].XValueType = ChartValueType.DateTime;
curveChart.Series["Series2"].Points.AddXY(DateTime.Now, 5.00m);
curveChart.Series["Series2"].Points.AddXY(DateTime.Now.AddDays(1), 7m);
curveChart.Series["Series2"].ChartType = System.Windows.Forms.DataVisualization.Charting.SeriesChartType.Line;
curveChart.Series["Series2"].BorderWidth = 3;
curveChart.ChartAreas["0"].AxisX.Interval = 1;