[Yaffs] problem in creating yaffs image

Hi,
I'm trying to use YAFFS on my project,I've downloaded YAFFS code from
CVS and patched kernel to enable YAFFS support.

Now, I can use flash_erassall in MTD tools to erase partition ,copy
files into that partition and boot as root filesystem.

The problem I encountered was I can't create image with
mkyaffsimage/mkyaffs2image, the procedure is:
on PC
1. mount a ext2 image we used as root filesystem before to directory WORK/
2. mkyaffsimage WORK root.yaffs (mkyaffs2image 1 WORK root.yaffs)
on target
3. flash_eraseall /dev/mtd5
4. nandwrite -a -o /dev/mtd5 root.yaffs

I can mount this partition but all I get is a lost+found directory
with something inside.

My target system is Linux-2.6.11,AMD au1200 with Infineon 64MB nand flash.

Is there anything I do wrong ? I've checked the mail list archive but
can't get anything helpful, please give me a direction.

Thanks for you help.

Best regards,

Will