troubles with isofs linux-2.5.5-xfs-dj2

[svetljo]

Hi
i'm having strange troubles with isofs in linux-2.5.5-xfs-dj2
compiled in i got ' iso9660 filesystem not suported by kernel '
compiled es module ( with or without zisofs)
[root@svetljo linux-2.5.5-xfs-dj2-2]#modprobe isofs
/lib/modules/2.5.6-pre1-xfs-dj2/kernel/fs/isofs/isofs.o: couldn't find 
the kernel version the module was compiled for
modprobe: insmod /lib/modules/2.5.6-pre1-xfs-dj2/kernel/fs/isofs/isofs.o 
failed
modprobe: insmod isofs failed
[root@svetljo linux-2.5.5-xfs-dj2-2]# insmod --force isofs
Using /lib/modules/2.5.6-pre1-xfs-dj2/kernel/fs/isofs/isofs.o
/lib/modules/2.5.6-pre1-xfs-dj2/kernel/fs/isofs/isofs.o: couldn't find 
the kernel version the module was compiled for
[root@svetljo fs]# uname -a
Linux svetljo.st-peter.stw.uni-erlangen.de 2.5.6-pre1-xfs-dj2 #13 SMP 
Fri Mar 1 22:09:13 CET 2002 i686 unknown

i don't get it, what's wrong