Choose "EXCELLON" on the device drop-down box.And choose the layers 20(dimension), 44(drilles), 45(holes) .
(Sorry, may change to a English operating interface later.)
To avoid this problem happen again, we suggest you download the newest CAM software from our website. We have already set the specification of CAM, then you can directly export the gerber file with correct Drill drawing layer.
If you still have problem to export the drilling layer, feel free to contact us.