In new server today created a authorized_keys file in /root/.ssh/ directory. After doing ssh first time got the error – Agent admitted failure to sign using the key
For solving this issue use the command ssh-add in client machine

ssh-add

Given below are the outputs from terminal. The solution pretty much straight simple.

sharad@mypc:~$ ssh root@192.168.156.11
Agent admitted failure to sign using the key.
root@192.168.156.11's password:

sharad@mypc:~$ ssh-add
Identity added: /home/sharad/.ssh/id_rsa (/home/sharad/.ssh/id_rsa)
sharad@sharad-sapplica:~$ ssh root@192.168.156.11
Last login: Tue May 28 08:52:15 2013 from 192.168.156.23
[root@server1 ~]#