Having a series with datetime x values and labels, the horizontal axis draws datetime values instead of the labels:

            Chart1.legend.visible=false;
            var series=Chart1.addSeries(new Tee.Line(Chart1)).addRandom(200);
            var msecsInADay = 86400000;
            var today=new Date().getTime();

            series.data.x=[];

            for (var t=0; t<series.count(); t++) {
                series.data.x[t]=new Date(today + t * msecsInADay);
                series.data.labels[t] = 'a';
            }

Also note this case causes overlapping because the 'a' text is used to calculate the internal increment, but the datetime values are longer.

Even forcing the "mark" or "text" labelStyle doesn't help to force showing the labels in the bottom axis:

            Chart1.axes.bottom.labels.labelStyle = "text"; //"mark"