请教如何使用友善自带的uboot

请问大家  我用mini2440 64M 的nand的板子，我将光盘中自带的uboot通过vivi的a项功能烧到NAND中结果不能启动内核，为什么啊?
NAND read: device 0 offset 0x50000, size 0x200000
reading NAND page at offset 0x50000 failed
Could not read entire image due to bad blocks
2097152 bytes read: ERROR
## Booting image at 30008000 ...
Bad Magic Number

我用自带的supervivi的启动信息是
Copy linux kernel from 0x00050000 to 0x30008000, size = 0x00200000 ... done
zImage magic = 0x016f2818
Setup linux parameters at 0x30000100
linux command line is: "noinitrd root=/dev/mtdblock2 init=nuxrc console=ttySAC0"
MACH_TYPE = 782
NOW, Booting Linux......
Uncompressing Linux........................................................................................................ done, booting