[U-Boot] "nand write.yaffs" is not working as expected

I'm recently using YAFFS2 rootfs on our NAND flash. What I'm experiencing is that the u-boot console "nand write.yaffs" is not working. With this image file, I can successfully write it to nand flash if I boot into Linux. In Linux console, I run "nandwrite -a -o /dev/mtd4 yaffs2.img". And then, I can mount the partition and see what's in it.

In u-boot, with the same yaffs2 image, I'm using "nand write.yaffs ${loadaddr} ${nandrootoffset} ${filesize}", and then I boot into Linux. I can only see a "lost+found" directory on that partition, nothing else.

Anyone ever met the same problem with this "nand write.yaffs" command? I'm wondering maybe I did something wrong?