Dang man! What in the hell? Did you ever call or write them and ask them to verify that you are indeed building up pref. points?
I've been selected twice in the last 6 years.
You can call them about your preference points. Lots of people lost theirs for awhile a few years back when they went from the SSN to a Drivers License # and people didn't read the small print to get them transferred.
Now they require both, so you should have gotten your points back. Give them a call and see what gives. They were pretty friendly to me when I called about the same thing a couple of years ago.