Deploying spree on heroku gives me this errors

errors.sh

the-crab$ git push heroku master
Counting objects: 970, done.
Delta compression using up to 4 threads.
Compressing objects: 100% (829/829), done.
Writing objects: 100% (970/970), 5.09 MiB | 327 KiB/s, done.
Total 970 (delta 110), reused 0 (delta 0)

-----> Ruby/Rails app detected
-----> Using Ruby version: ruby-1.9.3
-----> Installing dependencies using Bundler version 1.3.2
       Running: bundle install --without development:test --path vendor/bundle --binstubs vendor/bundle/bin --deployment
       Fetching gem metadata from https://rubygems.org/.......
       Fetching gem metadata from https://rubygems.org/..
       Could not find ransack-0.7.3 in any of the sources
 !
 !     Failed to install gems via Bundler.
 !
 !     Heroku push rejected, failed to compile Ruby/rails app

To [email protected]:coffeetailor.git
 ! [remote rejected] master -> master (pre-receive hook declined)
error: failed to push some refs to '[email protected]:coffeetailor.git'
MacBook-Pro:coffeetailor the-crab$