acts_as_list plugin not error in production

I'm having an issue where acts_as_list is not being loaded. I have it
in my vendor/plugins dir and it works great in dev mode. But after
deployment using Capistrano I am getting the following error in
production: NameError (undefined local variable or method
`acts_as_list' (full error: http://pastie.org/223658 ). I have
verified that the plugins exist in the "current/vendor/plugins"
directory on the production server. Any idea why acts_as_list wouldn't
work only in that setting?

That subject should have been "acts_as_list plugin error in
production" btw.

Success! I didn't realize you had to add git powered plugins as
submodules and also add git_enable_submodules to your deploy file.