Pb with NAND flash and ftl_format

Hi all,

I work with a nand flash with 4 partitions.

# cat /proc/mtd
dev:    size   erasesize  name
mtd0: 00400000 00010000 "physmap-flash.0"
mtd1: 04200000 00020000 "Linux"
mtd2: 09c00100 00020000 "Apps"
mtd3: 10000000 00020000 "Data"

When I try to format /dev/mtd1 with an ftl_format it gives me :

# ./ftl_format /dev/mtd1
Partition size = 66 mb, erase unit size = 128 kb, 1 transfer units
Reserved 5%, formatted size = 64853504 bytes
Erasing all blocks...
+++++++*+++++++*+++++++*+++++++*+++++++*+++++++*+++++++*+++++++*++
Writing erase unit headers...
write failed: Invalid argument
format failed.

And dmesg :

# dmesg
nand_write: Attempt to write not page aligned data

I 'm not sure to understand what it means.
I suppose that the problem comes with a difference between the adressing of the data and the size of the data but I don't know how to do ?

Here is my mtd_debug info :

# ./mtd_debug info /dev/mtd1
mtd.type = MTD_NANDFLASH
mtd.flags =
mtd.size = 69206016 (66M)
mtd.erasesize = 131072 (128K)
mtd.oobblock = 2048 (2K)
mtd.oobsize = 64
mtd.ecctype = MTD_ECC_SW
regions = 0

as somebody has an idea to fix my problem ?

Thank you.

Michel