Rails engine gem: Run Configuration Error: Rails server launcher wasn't found in project

Using 4.0.1 on OSX Lion.

I have a rails engine gem, with an embedded test app which is used to test the app, built using "rails plugin new mygem --full".

Upon opening in RubyMine:

[rake --tasks] ** Invoke load_app (first_time)

** Execute load_app

However "raks --tasks" works fine from the command line.

And there are no default configurations. If I add one, I get the error "Run Configuration Error: Rails server launcher wasn't found in project" at the bottom of the configuration dailog.

The gem's root contains script/rails which loads test/dummy/script/rails. Running the server works fine from the command line. I'm using bundler and have that box checked in the RubyMine configuration.

Seems like this error is misleading, and that RubyMine is actually looking for something more.