I’m pretty sure that some of the initial firmwares for the A3 series didn’t support jitter, but later revisions supported it. If it’s not supported in firmware from LiteOn’s site, then you will have to use the test firmware provided here on the forum, as I have seen jitter done in CD-DVD Speed and LiteOn’s own tools [maybe even DVDInfoPro] with drives different members have here.
I suggest you get the latest test firmware from the test firmware thread. The firmwares there are straight from LiteOn, and won’t cause your drive any harm. Test firmware: http://club.cdfreaks.com/f44/liteon-dh20a3-test-firmware-results-discussion-227621/
After you do that, try different versions of CD-DVD Speed, making sure that you have set the drive to scan jitter in the “Advanced” options of the Disc Quality tab. If different versions don’t work, use LiteOn’s tools.