Help ME, Please

I want to login in remote server, git server, with two accounts (mars and gitolite) without password. e.g. (steps)

1. ssh-keygen  # no password
2. scp .ssh/id_rsa.pub gitolite@gitserver:/tmp/
3. ssh gitolite@gitserve
4. cat /tmp/id_rsa.pub >> .ssh/authorized_keys
5. exit

Then, do :

ssh gitolite@gitserver ls 

But error message occurs:  
Permission denied (publickey,gssapi-keyex,gssapi-with-mic,password).

However, when cat the id_rsa.pub to the end of mars account's .ssh/authorized_keys, that's OK. Why?

Please help me !

Thank you so much.