I have the same problem, I followed the above instructions to the point. This is hindering my player flow allot as I just changed my IP to a dedicated IP. I can't report my server with the new IP because it is in use by a server that hasn't even been up for over 2 weeks.
I suggest Permissions Bukkit, you can edit all perms and groups and users, from within the game using commands. Then use essentials to set up your prefixes. Its all very simple. If you need any help let me know!