Due to the way template handling works in Rails 2.2, activeScaffold does not work on edge rails anymore.
Thanks to Dr.Gaffo there is fix for the problem in his fork of ActiveScaffold. Get the edge branch of his fork at http://github.com/gaffo/active_scaffold/tree/edge which is compatible with edge Rails.
Even after this you might face some problems like the path to Inflector. Just move the reference to ActiveSupport::Inflector and you should be good.
There is one issue that I noticed, date time field handling by ActiveScaffold is broken, thanks to refactoring in Rails core for handling these. I will post a fix for this as soon as possible and update this post too.