When I was using my Wingman Forcefeed back joystick (the same as yours Lugia2002) I had the controller type set to digital/analog in the pad config. If I set it to anything else, the pad wouldn't rumble. Try setting controller type to digital/analog and see if that helps. Also, be sure to check your drivers and DX version, as Bgnnome said. DX 7.0a or 8.0a work best w/that rumble pad.
sincerely,
sx/amiga