[Yaffs] Benchmark errors

Hi all,

when I benchmark the NAND with Bonnie++, I receive many
errors:

nand_write_oob: Failed write verify, page 0x0....
     :                  :                :
     :                  :                :

and Bonnie++ end with this messages:

Bonnie: drastic I/O error (rmdir): Directory not empty
Cleaning up test directory after error
Bonnie: drastic I/O error (rmdir): No such file or directory

Initially, I thinked that a problem of Bonnie++, but if I
run Bonnie++ on a NAND with JFFS2, I don't receive any
errors.

Why?

Thanks.