Do you have any problem with mongo in mac?

node app.js
[08-12-2014 20:11:19] - INFO: ------------------------------------------
[08-12-2014 20:11:19] - INFO: Starting BitBot v0.9.4
[08-12-2014 20:11:19] - INFO: Real Trading Enabled = true
[08-12-2014 20:11:19] - INFO: Working Dir = /Users/leonardo/Sites/BitBot
[08-12-2014 20:11:19] - INFO: ------------------------------------------
[08-12-2014 20:11:19] - INFO: Downloader started!

/Users/user/Sites/BitBot/node_modules/mongojs/node_modules/mongodb/lib/mongodb/mongo_client.js:409
          throw err
                ^
Error: failed to connect to [localhost:27017]

I tried localhost, 127.0.0.1. Sometimes the bot works, sometimes doesn't work. Any idea?