no such file to load -- activesupport (LoadError)

I can't get the db2s3 gem to run on my rails 3 application.

  /usr/lib/ruby/gems/1.8/gems/db2s3-0.3.1/lib/db2s3.rb:1:in `require': no开发者_StackOverflow中文版 such file  to  load -- activesupport (LoadError)
from /usr/lib/ruby/gems/1.8/gems/db2s3-0.3.1/lib/db2s3.rb:1
from /usr/lib/ruby/gems/1.8/gems/bundler-1.0.0/lib/bundler/runtime.rb:64:in `require'
from /usr/lib/ruby/gems/1.8/gems/bundler-1.0.0/lib/bundler/runtime.rb:64:in `require'
from /usr/lib/ruby/gems/1.8/gems/bundler-1.0.0/lib/bundler/runtime.rb:62:in `each'
from /usr/lib/ruby/gems/1.8/gems/bundler-1.0.0/lib/bundler/runtime.rb:62:in `require'
from /usr/lib/ruby/gems/1.8/gems/bundler-1.0.0/lib/bundler/runtime.rb:51:in `each'
from /usr/lib/ruby/gems/1.8/gems/bundler-1.0.0/lib/bundler/runtime.rb:51:in `require'
from /usr/lib/ruby/gems/1.8/gems/bundler-1.0.0/lib/bundler.rb:112:in `require'
from /home/sean/chief/config/application.rb:7
from /usr/lib/ruby/gems/1.8/gems/railties-3.0.0/lib/rails/commands.rb:28:in        `require'
from /usr/lib/ruby/gems/1.8/gems/railties-3.0.0/lib/rails/commands.rb:28
from /usr/lib/ruby/gems/1.8/gems/railties-3.0.0/lib/rails/commands.rb:27:in `tap'
from /usr/lib/ruby/gems/1.8/gems/railties-3.0.0/lib/rails/commands.rb:27
from script/rails:6:in `require'
from script/rails:6

I found that it was fixed in some of it's forks: http://github.com/masterkain/db2s3/commit/fe65d3f5fbe42e1a33cd5924e7fbf450b1f57c9e

But check out another forks too...

PS. I don't know alternative, but I've seen backup gem, that used to do the same thing, and even more.