[Yaffs] yaffs2 compile problem with 2.6.16.19 kernel

hi , My problem is after I patched the kernel , compile the modules ,there
is the message:

  LD [M]  /root/job/fs/yaffs2/yaffs2.o
  Building modules, stage 2.
  MODPOST
*** Warning: "yaffs_CheckpointOpen" [/root/job/fs/yaffs2/yaffs2.ko]
undefined!
*** Warning: "yaffs_EraseBlockInNAND" [/root/job/fs/yaffs2/yaffs2.ko]
undefined!*** Warning: "yaffs_InitialiseNAND"
[/root/job/fs/yaffs2/yaffs2.ko] undefined!
*** Warning: "yaffs_ReadChunkWithTagsFromNAND"
[/root/job/fs/yaffs2/yaffs2.ko] undefined!
*** Warning: "yaffs_WriteChunkWithTagsToNAND"
[/root/job/fs/yaffs2/yaffs2.ko] undefined!
*** Warning: "yaffs_CheckpointWrite" [/root/job/fs/yaffs2/yaffs2.ko]
undefined!
*** Warning: "qsort" [/root/job/fs/yaffs2/yaffs2.ko] undefined!
*** Warning: "yaffs_CheckpointClose" [/root/job/fs/yaffs2/yaffs2.ko]
undefined!
*** Warning: "yaffs_CheckpointInvalidateStream"
[/root/job/fs/yaffs2/yaffs2.ko]
undefined!
*** Warning: "yaffs_CheckpointRead" [/root/job/fs/yaffs2/yaffs2.ko]
undefined!
*** Warning: "yaffs_MarkBlockBad" [/root/job/fs/yaffs2/yaffs2.ko] undefined!
*** Warning: "yaffs_QueryInitialBlockState" [/root/job/fs/yaffs2/yaffs2.ko]
undefined!
  CC      /root/job/fs/yaffs2/yaffs2.mod.o
  LD [M]  /root/job/fs/yaffs2/yaffs2.ko

I get the yaffs.ko ,but I canot insmod it :

FATAL: Error inserting yaffs
(/lib/modules/2.6.16.19/kernel/fs/yaffs2/yaffs.ko): Unknown symbol in
module, or unknown parameter (see dmesg)

why ?

regards.