mount -t vfat /dev/sdb /zenwalk (also no output)
I'm not familiar with what you are trying to do, but that command can't be right. You need to mount a partition like so:
mount -t vfat /dev/sdb* /zenwalk
where the "*" corresponds to the partition number on the block device, /dev/sdb, eg:
mount -t vfat /dev/sdb1 /zenwalk
if the partition on sdb you want to mount is the first primary partition on sdb.