nandwrite problem

[Davide CASCONE]

I have a NAND device related to MTD block 5. The NAND device is correctly probing during the kernel boot phase. 
If I run the following commands

#mkdir /dev/mtdblock/5 b 31 5
#mount -t jffs2 /dev/mtdblock/5 /nand/

the JFFS2 file system is correctly mounting on the /nand/ directory.
But, if I run the following command

#./nandwrite -j /dev/mtdblock/5 filesys.jffs2_nand

in order to copy a file system image on the NAND device, the system returns the following message:

MEMGETINFO: Inappropriate ioctl for device

Any suggestions to solve the problem?

Thanks in advance,
Davide