Was this used for anything else?
The FAT (File Allocation Table) is a partition of the SD card that is used at boot time. If you connect the SD card to a MAC of PC, you will see some files on it. The rest of the card is using a linux file system.
For some reason th FAT couldn't be created. If you put a Micro SC card into a SD Adapter, check to see if the adapter as a lock switch. If it is locked, then the card can't be written to.
You could try formating it on your MAC or PC and then try using it with the SD cloner again.