nfs booting

[cjjoy1980]

I have enabled nfs booting on ppc based embedded board.  I had placed my kernel and rootfs in tftp directory, and had set the u-boot enivironment varialbes as:
   setenv bootfile /image/kernel
   setenv root_path /tftpboot/image

The board was booting with this configuration...

Now I have placed the kernel image and rootfs in /exports directory and have set the uboot variables as:
   setenv bootfile /exports/image/kernel
   setenv root_path /exports/image

I am not able to boot the board with the above directory.  I am getting the error

       Loading: T
       TFTP error: 'File not found' (1)
       Starting again.

May I know what could be the problem??