Heroku install: missing gem isn't missing

Trying to deploy an app to Heroku -- first time开发者_JAVA技巧 app and deployment -- and keep getting the following error when I'm trying to migrate the db:

Missing these required gems:
  authlogic  

You're running:
  ruby 1.8.7.253 at /usr/ruby1.8.7/bin/ruby
  rubygems 1.3.7 at /home/slugs/327637_0db78d3_8f84-7ba6678a-ff5d-4646-8320-f58c88156465/mnt/.bundle/gems/ruby/1.8, /home/slugs/327637_0db78d3_8f84-7ba6678a-ff5d-4646-8320-f58c88156465/mnt/.bundle/gems, /home/slugs/327637_0db78d3_8f84-7ba6678a-ff5d-4646-8320-f58c88156465/mnt/.gems, /usr/ruby1.8.7/lib/ruby/gems/1.8

Run `rake gems:install` to install the missing gems.
(in /disk1/home/slugs/327637_0db78d3_8f84-7ba6678a-ff5d-4646-8320-f58c88156465/mnt)

Running "rake gems:install" doesn't do anything. (It returns the directory path.) I've run "rake gems" to check what's installed, which returns:

 - [I] authlogic 
    - [R] activesupport 

I = Installed
F = Frozen
R = Framework (loaded before rails starts)

I've also restarted the Heroku server, but with no luck. I know there are tons of similar questions already posted, but I'm not super comfortable in the command line yet and can't decipher the differences in error messages and solutions. Does anyone have an idea what's going wrong here?

Thanks in advance.

@shingara is right about the .gems files. This is a file that heroku uses in rails 2.x apps so it knows what gems to load.

You'll want to do

Create your .gems file: Your .gems file should look like

rails --version 2.3.9
authlogic
paperclip --version 2.3.1.1

Now:

git add .gems
git commit -m 'added gems manifest file'
git push heroku

More information at Heroku Gems