thanks a lot for the wuick reply.
i tried to do it without chroot but it did not worked. then i did it through chroot and here is the output:
Knoppix:/# grub-install --recheck --no-floppy --root-directory=/ /dev/hda
Probing devices to guess BIOS drives. This may take a long time.
/sbin/grub-install: line 389: /dev/null: Permission denied
/dev/hda does not have any corresponding BIOS drive.
Knoppix:/#

grrrrrrrrrrrr. what is wrong?