Make sure that the chart uses 3D axis fitting:
NCartesianChart chart = (NCartesianChart)nChartControl1.Charts;
chart.Fit3DAxisContent = true;
chart.BoundsMode = BoundsMode.Fit;
If that does not solve the problem most likely the problem resides in how you configure the chart layout. To verify this enable the content area filling temporarily:
chart.BackgroundFillStyle = new NColorFillStyle(Color.Gray);
and check if the gray area goes outside the control bounds.
Hope this helps - let us know if the problem persists.
Nevron Support Team