Can't config replica set using MongoDB 3

I'm trying to create a replica set in MongoDB version 3.04. I followed this tutorial and getting the next error while trying to add nodes using the primary server:

vacrep:PRIMARY> rs.add('server address here')
{
    "ok" : 0,
    "errmsg" : "Quorum check failed because not enough voting nodes responded;
     required 2 but only the following 1 voting nodes responded: PRIMARYSERVER:27017; 
     the following nodes did not respond affirmatively: 'server address here':27017 
     failed with Missing credentials for authenticating as internal user",
     "code" : 74
}

This is what been done so far:

1. Install 3 servers with MongoDB 3.04
2. Run all MongoDB instances with repSet mode
3. Verified connectivity between servers using this approach
4. Initiate a replica in the primary server)

I found few threads about this error no but couldn't find a solution in any of them. How can I solve this?

Found the solution - It was permission issue.

In MongoDB configuration file, I had to turn off authentication mode or create a shared key between all nodes using this guide:

https://docs.mongodb.com/manual/tutorial/deploy-replica-set-with-keyfile-access-control/#deploy-repl-set-with-auth

This was the reason my servers couldn't communicate each other.