Unibeast unable to create usb boot

Hi,

I purchased a legit copy of Mountain Lion on the apple store.
Whenever I try to create a usb drive with Unibeast it says:

"Your selected Mac OS X Installer is incomplete.
Please delete all copies of the installer from all mounted volumes and redownload it again from the Mac App Store."

I dont have any mounted volumes aside from the usb key i'm trying to make a boot on.

Thanks

Problem solved ! I erased ML application setup and downloaded it again.

but now after install i can only boot ML into safe mode with no sound no ethernet, only mouse and keyboard (after 5 minutes of unrecognized Keyb& mouse)
And when I try to set up Multibeast (Mountain Lion Edition) it says "Installation Failed".
So unable to install Chimera.

Boot in Regular mode displays the grey apple logo with an endlessly spinning grey wheel.