If you look at the version history, complete HD20 support was only added with v1.3.2. That particular version is still lost, but we do have 1.7.1, so I would recommend trying again with that. Remember, 1.7.1 is just a control panel, so just toss that into the System Folder and you should he good to go (just make sure to remove both the v1.2 Rapport init and the Rapport Prefs cdev first).
EDIT: Also, make sure that the HD20 is plugged into the mac first, then the dongle behind the HD20. (I would test with my own HD20, but its drive is not responsive.)