I've always been leveled. Sometimes I've had to call, but if they assign you a trip, you get leveled.
From my experience, the company doesn't really care about leveling for the most part. Whether you fly the trip or the next guy really isn't that important (to them). They don't give you any credit toward RLG and you are still available to fly trips if they get to your name.
I'd say contract enforcement is wrong on this one. They are confusing credit toward RLG and leveling.
If it were me, I'd call back and ask to speak to the scheduler. If it's the one that you had problems with, I'd just hang up. If they can't fix it, I'd call enforcement again. It is very cut and dry in this very "grey" contract that you get leveling upon assignment. Quote the specific text.