[Yaffs] Ask for help on "mount -t yaffs2"

Hi, all. I am a newbie of YAFFS2, and of Linux file systems. I followed the

steps on
http://www.yaffs.net/lurker/message/20091011.221340.05de674a.da.html
but something wrong happened at the last step.
When I try to run "mount -t yaffs2 /dev/mtdblock0 xxx", the error appears;
it says,
"mount: wrong fs type, bad option, bad superblock on /dev/mtdblock0,
       missing codepage or helper program, or other error
       In some cases useful info is found in syslog - try
       dmesg | tail  or so
"

It seems yaffs2 is not the right fs type. But "cat /proc/filesystems" shows
that yaffs and yaffs2 exist.

I have tried under Ubuntu 9.04 and Ubuntu 8.04, and this error always
appear. Can you give me some suggestion? Your replies are greatly
appreciated.

Thank you so much!

dongle