Using Apple configurator to up/downgrade iOS

Hi,

I just received my new batches of new iPad 4 (Air WiFi) for my company. They were running iOS 7.1 but all existing batch of iPad were running iOS 7.1.2. I would like to keep all devices using the same iOS version, is they a way to do this with Apple Configurator (I am using 1.6)? I got these problems:

1. To get supervised device, Apple Configurator can only download and install the latest version (8.0.2 at the moment and left me no choice)
2. I had read http://support.apple.com/kb/HT200241?viewlocale=en_US, which told me how to select a custom iOS firmware instead the latest version
3. I used IPSW from my local cache(7.1.2) and “Prepare” the device for supervise
4. The process stopped just right after Apple Configurator try to install the OS. Apple configurator got error 3194 and the iPad was left in recovery mode and could not be rebooted(Thank for a tool - Tiny Umbrella safe me from the recovery mode)

Regards,

David