Obtaining NAND oobinfo

[bandwidthcrunch]

Hi All,
         Any clues why 
./flash_eraseall -j /dev/mtd3 
./flash_eraseall: /dev/mtd3: unable to get NAND oobinfo

should happen ?  
cat /proc/mtd shows
dev:    size   erasesize  name
mtd0: 00040000 00040000 "Bootloader"
mtd1: 00100000 00040000 "Kernel"
mtd2: 01ec0000 00040000 "Filesystem"
mtd3: 02000000 00004000 "Filesystem on nand"

and dmesg shows
NAND device: Manufacture ID: 0xec, Chip ID: 0x76 (Samsung K9D1208V0M)
Creating 1 MTD partitions on "Samsung K9D1208V0M":
0x00000000-0x02000000 : "Filesystem on nand"

Any suggestions would be great 
regards,
band