Originally Posted by FBinNY

Since it's the adapter, focus on that.

However (sorry if it's been said) what kind of fork? Specifically, is the steerer steel, aluminum, or carbon fiber? I ask because anything but steel limits how tight you can go.

Back to the adapter, pull it out and tighten off the bike to verify that the wedge can slide up well beyond what you'll need. If not, the problem is a bad thread on the draw bolt.

Now grease the thtreads on the draw bolt, confirm that it's a snug fit in the fork before tightening, and tighten. I cannot imagine that it can't hold much tighter than the race tight I described earlier.