problem with data persistence on nand

Hi all,

i am trying to mount nfs on mini2440 using uboot and all things are going
good like i am able to mount nfs.
but what problem i am facing is that on every restart of my MINI2440 board
all my nand just becomes erased so i have to set all the things again.
Is there any way with which i can overcome this problem, anyhow i need my
data should be in nand even after restart of board. 

thanks in advance.

regards
dayal

fix it..