JfreeChart, how to show only 2 tick units at default position on NumberAxis?

Question

Im trying to only show 2 ticks on my subplots number axis, but i just cant get it to work. Any help on how to do this would be greatly appreciated!

I want to have 1 tick unit at value 20 and the other at 80.

 private NumberAxis getRsiValueAxis() {
    final NumberAxis rangeAxis2 = new NumberAxis(ChartConstants.RSI_AXIS_LABEL);

    rangeAxis2.setRange(0, 100);
    rangeAxis2.setAutoRange(false);

    TickUnits units = new TickUnits();
    units.add(new NumberTickUnit(20));
    units.add(new NumberTickUnit(80));

    rangeAxis2.setStandardTickUnits(units);

//  rangeAxis2.setTickUnit(new NumberTickUnit(20));
    return rangeAxis2;
}