Problem with diskette drive

The led of my diskette drive is always on. During the boot sequence, a message from setup says "Floppy disk fails (40). In the control panel, this disk is named as removable disk. But in the boot menu of the setup, when "boot up floppy disk seek" is disabled, the disk is normally named as "floppy disk" in the control panel, but nevertheless the floppy inside is not detected. I know the cable is not turned the wrong way. I had my processor upgraded from 350 khz to 933 khz with a new motherboard and the diskette drive worked immediately thereafter. It seems ther's also a problem when I try to use a Iomega drive, Windows won't boot.
A lot of thanks for your help.

Hmmmm,Light always on usually is cable wrong way,but maybe its just come loose?