These are a little harder to plug in, and may take some rocking. Floppy cables have a twist in the cable. You need to use a cable with the proper connectors for each type you use.
Many floppy cables come with connectors for each type on each side of the twist.
Always check Pin 1 on the ribbon cable connector. The red edge of the cable is connected to Pin 1. If you accidently reverse this, your drive won't be damaged, it just won't work, and the floppy drive light will stay on all the time until fixed. Consult your motherboard's manual to determine which is your floppy controller. Double Check your work.