Lync on Mac loggin in from extranet not from intranet

Hi,

i'm trying to use Lync (14.0.5 - 130524) on my Mac OS 10.8.4

After several attempt i'm now able to connect correctly using my corporate USER NAME/PASSW (AD) only is using the extranet connection, if i'm in my office i cannot.

Mind i use daily office communicator 13.1.3 for Mac

Thank you in advance