I've been debugging this line of code for so log... 

Even though the env variables listed in the `heroku config`, it's not existing during `assets precompile` process... yet the default ones Heroku provided like GEM_PATH or LANG are still there.

```
➜  knojoe git:(pusher_on_production) heroku config
=== knojoe Config Vars
GEM_PATH:                    vendor/bundle/ruby/1.9.1
LANG:                        en_US.UTF-8
PATH:                        bin:vendor/bundle/ruby/1.9.1/bin:/usr/local/bin:/usr/bin:/bin
PUSHER_APP_ID:               111
PUSHER_KEY:                  222
PUSHER_SECRET:               333
```

After I solved the problem I was like this ↓↓↓↓

![dajia](https://f.cloud.github.com/assets/184520/404997/d3f55b80-a9a4-11e2-8163-e3c41519c071.gif)