Using a USB ****t from DOS

I need to use the laptop computer's USB ****t, and I was given the
names of some drivers which are known to do that: usbaspi.sys and
di1000dd.sys.

I downloaded them from the web, and I downloaded from www.bootdisk.com
the boot files for WinME, bought a copy of Nero so that I could create
a bootable CD, and combined the boot disk with the USB drivers** to
make a CD that booted.

**I put those files in the root directory of the CD and put hese lines
in config.sys:
device=usbaspi.sys /w /v
device=di1000dd.sys

While the laptop boots from the CD, it asks for my USB device (a
memory stick), just like I wanted it to.

It found the memory stick, but didn't assign a drive letter to it!!!
It started DOS, and I tried every letter, but I couldn't find it.

I've tried this several times.

Then I tried this same CD on my fully functioning desk computer, and
it did the same thing.  It found the memory stick, but didn't assign a
letter to it!!

OTOH, if I run windows 98SE on my desk CD, it has no trouble finding
the stick and assigning a letter!

What do think I have done wrong?  :) 

If you are inclined to email me
for some reason, remove NOPSAM  :-)