vfat not recognized in debian

mount use libblkid to guess the filesystem from the device you're trying to mount, and you can see that it work from the error message it give:

mount: unknown filesystem type 'vfat'

but the weird thing here is that if the required filesystem is in a module that isn't yet loaded, mount try to auto-load the module using modprobe.

So my only guess so far is that something is wrong with your kernel modules:

/lib/modules/3.2.0-4-686-pae/kernel/fs/fat/vfat.ko
/lib/modules/3.2.0-4-686-pae/kernel/fs/fat/fat.ko

edit

or for some reason mount fail to execute modprobe.