That was designed using the files to root 2.1 only, why would you expect it to work?
If memory serves right, an update to Easyroot was issued about a month ago when Froyo first leaked that made it work for the leak.
Here is a update from the Easy Root website:
This are a bit unclear for you guys at this time. With the /boot partition getting locked down for now and no “real” recovery partition it makes life a bit difficult. The official 2.2 update will remove your root and block tools like Easy Root. Once the official 2.2 OTA hits we will see what our options are. So, this post will get updated later for the Droid X when the official OTA hits, but the key thing to get out of this…get away from official ROM’s from Verizon/Motorola. They will constantly try and stop you from using your phone as you like. If you have a Droid 1, get CyanogenMod and enjoy having root and faster more open phone.