It's not possible to install Windows 7 (+) to Fat /Fat32 format Drive
It's not possible to install onto FAT32 but you can use it to install.
@Batu. did you try using Windows 7 to do the job?
i think the issue may be a filesize limitation on FAT32, install.wim is 4.3GB in the W8x64_Developer.iso, if memory servers, FAT32 has a 2GB or so limit......