Help!

[soni]

I just downloaded the Demo for Amnesia: the Dark Descent. I was so incredibly excited to play but when i click it, a message comes up saying:

Could not load main init file: config/main_init.cfg

Ive tried restarting my computer, verifying the integrity of the download, and re-downloading it thrice, but to my dismay, nothing Im running it on a Mac with a 2.5GHz Intel Core i5 processor and Intel HD Graphics 4000 1024MB (if this helps any...)
Watching the trailer makes me want to play so badly, if anyone can provide any instruction on how to fix this problem, it'd be greatly appreciated.