WIndows 98 System Backup

I have just reinstalled everything, with reformatting C: and reinstalling
Win98 SE and the usual applications. I have a floppy drive A: and a Zip
drive, D:. Now when I go to Accessories/System Tools/ Backup, I am told that
there is no backup device installed and if I continue, it doesn't show me
either A: or D: as places I may backup to; the only choice is to backup to a
file.

I've let Windows search for devices but it doesn't find anything.

The Zip drive works fine with Iomega software; the A: drive is available in
My Computer (as is the D drive) and I can use it. It's only in Backup that
they don't appear.

Before the reinstall, it worked fine.