permission denied after creating droplet using ssh keys

I created a new droplet using “Ruby on Rails on 14.04” and added SSH keys in stead of using root password. When I tried connecting through ssh I got these results :(

$ ssh xxx.xxx.xx.xxx
pc@xxx.xxx.xx.xxx's password: *************
Permission denied, please try again.
pc@xxx.xxx.xx.xxx's password: 

Then I tried:

$ ssh root@xxx.xxx.xx.xxx
root@xxx.xxx.xx.xxx's password: 
Permission denied, please try again.
root@xxx.xxx.xx.xxx's password: 

Then I tried:

$ ssh -i /path/to/.ssh/id_rsa_private_key root@xxx.xxx.xx.xxx
root@xxx.xxx.xx.xxx's password: 
Permission denied, please try again.
root@xxx.xxx.xx.xxx's password: 

I’m not sure what to do at this point … can you help me?