Linux/AM3352: UBIFS NAND booting problem

[ 1.428697] cpu cpu0: cpu0 clock notifier not ready, retry
[ 1.435119] UBI error: cannot open mtd 9, error -19
[ 1.440093] hctosys: unable to open rtc device (rtc0)
[ 1.454009] lis3_reg: disabling [ 1.457378] vbat: disabling
[ 1.462269] UBIFS error (pid: 1): cannot open "ubi0:rootfs", error -19VFS: Cannot open root device "ubi0:rootfs" or unknown-block(0,0): error -19
[ 1.475672] Please append a correct "root=" boot option; here are the available partitions:
[ 1.484212] 0100 8096 ram0 (driver?)
[ 1.488985] 0101 8096 ram1 (driver?)
[ 1.493654] 0102 8096 ram2 (driver?)
[ 1.498371] 0103 8096 ram3 (driver?)
[ 1.503039] 0104 8096 ram4 (driver?)
[ 1.507749] 0105 8096 ram5 (driver?)
[ 1.512417] 0106 8096 ram6 (driver?)
[ 1.517121] 0107 8096 ram7 (driver?)
[ 1.521791] 0108 8096 ram8 (driver?)
[ 1.526455] 0109 8096 ram9 (driver?)
[ 1.531161] 010a 8096 ram10 (driver?)
[ 1.535917] 010b 8096 ram11 (driver?)
[ 1.540710] 010c 8096 ram12 (driver?)
[ 1.545466] 010d 8096 ram13 (driver?)
[ 1.550262] 010e 8096 ram14 (driver?)
[ 1.555016] 010f 8096 ram15 (driver?)
[ 1.559822] Kernel panic - not syncing: VFS: Unable to mount root fs on unknown-block(0,0)
[ 1.568158] ---[ end Kernel panic - not syncing: VFS: Unable to mount root fs on unknown-block(0,0)

My partition in u-boot is 

#: name                                          size                     offset              mask_flags
0: NAND.SPL                            0x00020000         0x00000000               0
1: NAND.SPL.backup1             0x00020000          0x00020000              0
2: NAND.SPL.backup2             0x00020000          0x00040000              0
3: NAND.SPL.backup3             0x00020000          0x00060000              0
4: NAND.u-boot-spl-os              0x00040000         0x00080000              0
5: NAND.u-boot                        0x00100000          0x000c0000              0
6: NAND.u-boot-env                 0x00020000          0x001c0000              0
7: NAND.u-boot-env.backup1   0x00020000          0x001e0000             0
8: NAND.kernel                         0x00800000          0x00200000             0
9: NAND.file-system                  0x07600000          0x00a00000             0

My bootcmd is :

'console=ttyO0,115200n8 noinitrd ip=off mem=256M rootwait=1 rw ubi.mtd=9,2048 rootfstype=ubifs root=ubi0:rootfs init=/init'

The ubifs build-tool is the srcipt in SDK/bin/create-ubifs.sh

I follow this step:

1. go into u-boot

2. Get the custom ubifs via tftp: #  tftp xxx.ubifs

3. create ubi: #  ubi part NAND.file-system && ubi create NAND.file-system

4. # ubi write 0x82000000 0xa00000 $(ubifs_size)

5. # boot

Could you guys help me?