nodejs, Cannot find module './connection/read_preference' error with mongodb

I'm trying to run tests on an app created by a collegue and keep getting this error. The call is in the mongodb module on line 13

ReadPreference = require('./connection/read_preference').ReadPreference,

Have you any idea on why this happens?I Have mongo db running correctly.

It was an issue with mongoskin.

npm remove mongoskin

npm install mogoskin 

solved it