1) check that you have the latest version installed
2) open it up and go to console ... type "getinfo" and see if you have connections to the network .. if not .. you are probably firewalled or have another networking issue
3) if you are connected and the latest block counter is increasing .. then you are syncing ...
4) if you are connected but not syncing ... maybe reset your chain/peers database by deleting the corresponding folders somewhere in ~/Library/ apps bitsharesx .. (search the forum for this one)
5) and please .. would you be a little more precise with out issue instead of tell that "it is not working"!? would help the supports guys alot