GIT clone failed from a private GIT server

Hi there,
I have a MAC mini with Mavericks OS and I have some problems in logging in and when I try to GIT clone from a private GIT server. It is installed and configured to Ubuntu OS and I never had any problem to do this before. Why I can’t clone the server now ? How can I solve this and prevent it to happen again ? I didn’t change any settings before starting to make the clone.
Thank you !

Clone failed
Reason:
Server could not authenticate your identity. Please check that your SSH keys (as used in FAS) are set up correctly in Eclipse. How? Press, CTRL+3 then type ‘SSH2” and hit return. Also, make sure that you have the permissions required to attempt this action.
You may choose to clone anonymously, by selecting the relevant option. Note that push attempts will fail in this case.
OK
