pbs with matroxfb_* modules

I,

I'm working with:

debian/linux woody
Matrox g 400 32 Mo
kernel 2.4.18-686
xfree86-common Version: 4.1.0-16

Here is my pb :

When I load matroxfb_base module with the command :

me-at $ modeprobe matroxfb_base

then I can't unload it with with the command :

me-at $ rmmod matroxfb_base

it answer to me that it is busy but the lsmod command tell me it is
unused

an idea ?

PS : matroxfb_base is compiled in module
--
Philippe Monroux
Ile de la Reunion
E 55.3° S 21.5°