MEPIS doesn't automatically mount the usbdevfs filesystem, and its name was shortened a couple years back to usbfs. The development of udev has made it unnecessary for most purposes, but it's still in the kernel if you want it.
You can mount it manually with this (root user) command:
or add this line to /etc/fstab afer the proc entry
if you want it mounted automatically on each boot.
Once the usbfs is mounted, usbview works as expected.