I just replaced a fork with a different one (Bluto»Mastodon) and, after inserting the compression ring into the top bearing (it has a tapered section), the steerer tube still wiggles from side to side. The bearings are new so there's no chance they are damaged. The entire set-up worked just a few moments ago without any problems, but now I cannot seem to figure out how to get it to stop moving. What could be the problem?
Here's a photo: