Hi Irina,
Yes you need to set the min / max page sizes:
NCartesianChart chart = (NCartesianChart)nChartControl1.Charts[0];
NRangeSelection rangeSelection = new NRangeSelection();
rangeSelection.MinHorizontalPageSize = 1;
rangeSelection.MinVerticalPageSize = 1;
chart.RangeSelections.Add(rangeSelection);
NBarSeries bar = new NBarSeries();
bar.Values.Add(10);
bar.Values.Add(20);
bar.Values.Add(30);
chart.Series.Add(bar);
nChartControl1.Controller.Tools.Add(new NPanelSelectorTool());
nChartControl1.Controller.Tools.Add(new NDataZoomTool());
Let us know if you meet any problems.