Problem booting from MTD partition of NAND device

[Demke Torsten-atd012]

Hi all,

I have a PPC system that consists of several MTD partitions on a mix of
NOR and NAND flashes.
MTD partition layout in my system:
dev:    size   erasesize  name
mtd0: 00020000 00020000 "enviroment-flash1"
mtd1: 00500000 00020000 "kernel-flash1"
mtd2: 01a60000 00020000 "empty-flash1"
mtd3: 00080000 00020000 "uboot-flash1"
mtd4: 02000000 00020000 "boot-flash1"
mtd5: 00020000 00020000 "enviroment-flash2"
mtd6: 00500000 00020000 "kernel-flash2"
mtd7: 01a60000 00020000 "empty-flash2"
mtd8: 00080000 00020000 "uboot-flash2"
mtd9: 02000000 00020000 "boot-flash2"
mtd10: 80000000 00020000 "NAND Flash"

Partition 4 is the merge of partitions 0..3
Partition 9 is the merge of partition 5..8
0..4 and 5..9 are independent NOR flash devices (Intel Strataflash)
Partition 10 is located on a NAND flash device and is formated with
jffs2.

Whenever I try to boot from the NAND flash (root=/dev/mtdblock10)  I get
following error:
  VFS: Mount ROOT_DEV 0 - mtdblock10		<< some additional debug
output
  Kernel panic - not syncing: VFS: Unable to mount root fs on
unknown-block(0,0)

When I disable all NOR flashes in the kernel (2.6.14) I can boot
(root=/dev/mtdblock0) 
my board without a problem.
Any hints or comments?

Thanks for your help.
Regards,
Torsten