Problem accessing /dev/mtdblockn

[t kevin]

Hi,

I'm encountering a strange problem with Kernel version 2.6.36.
Accessing mtd device is fine but not the corresponding mtdblock device.

root at home:/tmp# dd if=/dev/mtd9 of=m9.bin
13247+1 records in
13247+1 records out
6782496 bytes (6.5MB) copied, 2.714321 seconds, 2.4MB/s

root at home:/tmp# dd if=/dev/mtdblock9 of=m9b.bin
attempt to access beyond end of device
mtdblock9: rw=0, want=13248, limit=13247
Buffer I/O error on device mtdblock9, logical block 6623
dd: /dev/mtdblock9: Input/output error

ls -l :
-rw-r--r--    1 root     root       6782496 Jan  1 21:19 m9.bin
-rw-r--r--    1 root     root       6778880 Jan  1 21:19 m9b.bin

mtdinfo
mtd9
Name:                          testos
Type:                           nor
Eraseblock size:                65536 bytes, 64.0 KiB
Amount of eraseblocks:          103 (6782496 bytes, 6.5 MiB)
Minimum input/output unit size: 1 byte
Sub-page size:                  1 byte
Character device major/minor:   90:18
Bad blocks are allowed:         false
Device is writable:             false



Please get me some clue what went wrong.

Thans a lot
Kevin