No filesystem could mount root

hello:

I was trying to transplant uClinux to DE2 for two weeks,I follow the wiki step by step!

and the error message is:

Kernel panic - not syncing: VFS: Unable to mount root fs on unknown-block(0,0)

After I found a lot of web page.I found the mistake was happen at romfs,because,when I do the order "make romfs",it says "nothing to do for romfs",and the romfs file is empty.

When I follow this web page,http://www.nioswiki.com/index.php?title=operatingsystems/uclinux/uclinuxdist/initramfsupdate&highlight=initramfs

I delete the romfs and make it again,the results is the same!

I think the problem is the rootfs,but I don't know how to resolve it.

I was using Ubuntu 9.10,quartus and IDE 8.1,and the uClinux-dist is uClinux-dist-20070130.tar.gz,and the my NiosII gcc cross compiler is nios2gcc-20080203,and it is successfull.

I have confused it for a few weeks,but I still resolve the problem,please tell me how to do,how to build the rootfs or how to transplant uClinux to DE2.Thank you very much!