Hi,
How was it installed?
How are you starting it?
How are you checking that it's not started (please keep in mind that installing YateServer from the dmg wont show anything in the GUI)
If you're starting it from command line, please provide a log.
If you installed it from the .dmg, try in Terminal the command 'telnet localhost 5038'. If it connects, Yate is running. If not, please provide some more info (do you see in Console any message regarding Yate? If so, please paste it here)