OSX - Synergy won't switch to the screen where the display has gone to sleep

Just got a new Haswell MacBookAir and I installed Synergy on it. I'm having trouble when the display goes to sleep as synergy won't switch to it to wake it up. Or maybe it will switch over there but it won't wake the screen.

I'm using a Windows 8 machine as the server and OSX 10.8 as the client.

Synergy 1.4.12

Any ideas? Is there a setting I'm missing?

Thanks