androidplot x axis isn't scaling

Question

With androidplot in android studio (kotlin), the x-axis (domain) doesn't work properly. It doesn't scale itself by integer X values. What am I missing here? Scale error on X axis:

val aa1= arrayOf<Number>(20,20,40,40)
val adom= arrayOf<Number>(60,120,120,580)
val series1 : XYSeries = SimpleXYSeries(Arrays.asList(* aa1),SimpleXYSeries.ArrayFormat.Y_VALS_ONLY
            ,"aa1");

val series1Format = LineAndPointFormatter(Color.BLUE,null,null,null)
plot.addSeries(series1,series1Format)

plot.graph.getLineLabelStyle(XYGraphWidget.Edge.BOTTOM).format = object : Format() {
            override fun format(obj: Any, toAppendTo: StringBuffer, pos: FieldPosition): StringBuffer {
                val i = Math.round((obj as Number).toFloat())
                return toAppendTo.append(adom[i])
            }

            override fun parseObject(source: String, pos: ParsePosition): Any? {
                return null
            }
        }