The start date and end date will then be displayed on the chart title. Please check to see if they are what you expect (that is, the two dates only differ by 30 days).
If even using hard coded dates, there are still to many labels, please make sure the there is no other lines that can add labels to the x-axis. For example, if your code calls Axis.setLabels, it will add more labels to the x-axis.
If the above still does not solve the problem, would you mind to inform me the charting part of your code?
If you do not have setXData(myTimeStampsArrray) to provide the x-coordinates, then ChartDirector will assume the x-coordinates are the array index of your data (that is, the x-coordinates are 0, 1, 2, 3, ). If you configure the x-axis using Axis.setLabels, ChartDirector will also assume the x-coordinates for the labels to be array index 0, 1, 2, 3, .. So the data points matches the labels.
For your case, if you configure the x-axis using Axis.setDateScale, you would need to provide the x-coordinates too by using Layer.setXData.