1. You've tried different drives, all with the same result.
2. You've changed the cable.
3. You get the drive not ready/format disk errors.
4. You're BIOS seems to recognize that a floppy drive is attached.
If all of the above is true, I'd go back to dmbfan819's hunch about a driver issue. If you go into Device Manager, is the drive reported to be working correctly there?